style: Fix all mypy errors and add type hints to untyped function bodies

**Resolved all 65 mypy errors across 14 files and added type annotations to all previously untyped function bodies. Final result: 0 errors with --check-untyped-defs enabled, all 454 tests pass.**

`scrapling/core/_types.py`

  - Removed broken Self = object fallback — now requires typing_extensions for Python < 3.11

`scrapling/core/storage.py`

  - Fixed str/bytes mismatch in _get_hash() — used separate _identifier_bytes variable instead of reassigning from str to bytes

`scrapling/core/custom_types.py`

  - split() return type: Union[List, "TextHandlers"] → list[Any] (avoids LSP violation with parent list[str])
  - format() kwargs: **kwargs: str → **kwargs: object (matches parent str.format signature)
  - AttributesHandler.__init__: Added mapping: Any = None, **kwargs: Any and -> None
  - json_string property: Added -> bytes return type

`scrapling/core/mixins.py`

  - Changed self: "Selector" to self: Any on all mixin methods (mypy can't handle forward-reference self types on non-subclass mixins)
  - Added Dict[str, int] annotation for counter variable
  - Removed unused TYPE_CHECKING / Selector imports

`scrapling/parser.py (~30 errors)`

  - Added body: str | bytes pre-annotation for dual-type if/elif assignment
  - Used Dict[str, Any] kwargs dict for HTMLParser(...) to bypass incomplete lxml stubs missing default_doctype
  - Changed base_url=url or None → base_url=url or "" (avoids str | None vs str | bytes)
  - bool(adaptive) to guarantee bool type for __adaptive_enabled
  - Declared __text: Optional[TextHandler], __tag: Optional[str], __attributes: Optional[AttributesHandler] at top of __init__
  - cast(List, ...) for all XPath() call results (_find_all_elements, _find_all_elements_with_spaces)
  - Added Dict[float, List[Any]] for score_table, Dict[str, Any] for attributes
  - Changed score, checks = 0, 0 → score: float = 0; checks: int = 0 (two locations)
  - Renamed target → target_element in save() to avoid variable redefinition with different types
  - Wrapped node_text.clean() / .lower() in TextHandler(...) to preserve type

`scrapling/engines/_browsers/_page.py`

  - Added PageInfo[SyncPage] | PageInfo[AsyncPage] union type annotation to page_info variable

`scrapling/engines/_browsers/_validators.py`

  - Convert method_kwargs (TypedDict) to plain Dict[str, Any] before dynamic key access

`scrapling/engines/_browsers/_base.py`

  - Added _config declaration to BaseSessionMixin
  - Used cast(StealthConfig, self._config) in __generate_stealth_options to access stealth-only attributes
  - Added Tuple[str, ...] annotation for flags
  - Removed redundant narrower StealthConfig type annotation on self._config in StealthySessionMixin.__validate__
  - Widened SyncSession and AsyncSession fields (playwright, context, browser) to Any to support both playwright and patchright types
  - Added -> None to both start() methods

`scrapling/engines/_browsers/_stealth.py`

  - Added Optional, ProxyType imports
  - Annotated proxy: Optional[ProxyType] in both sync/async fetch loops
  - Annotated outer_box: Any at first declaration, removed duplicate type annotations in subsequent branches
  - Added -> None to sync and async start()
  - Added config: Any parameter type to _initialize_context
  - Removed redundant self.context: AsyncBrowserContext re-annotations in conditional branches

`scrapling/engines/_browsers/_controllers.py`

  - Added Optional, ProxyType imports
  - Annotated proxy: Optional[ProxyType] in both sync/async fetch loops
  - Added -> None to async start()
  - Removed redundant self.context: AsyncBrowserContext re-annotations

`scrapling/spiders/request.py`

  - Added Optional import, typed _fp: Optional[bytes] = None
  - Removed redundant body: bytes re-annotation

`scrapling/spiders/session.py`

  - Used separate client variable instead of reassigning session = session._client (avoids type incompatibility and fixes a bug where session._make_request was called instead of client._make_request)
  - Added -> None to SessionManager.__init__

`scrapling/engines/toolbelt/convertor.py`

  - Added list[Response] annotation for history in both sync/async methods

`scrapling/engines/static.py`

  - FetcherClient.__init__ and AsyncFetcherClient.__init__: Added **kwargs: Any and -> None

`scrapling/core/shell.py`

  - Wrapped re_sub(...) result in TextHandler(...) to maintain correct type
  - Added -> None to CurlParser.__init__
  - Added full type signature to create_wrapper, replaced wrapper.__signature__ = ... with setattr(wrapper, "__signature__", ...) to satisfy mypy
  - Added Callable to imports

scrapling/engines/_browsers/_base.py

@@ -5,16 +5,12 @@ from contextlib import contextmanager, asynccontextmanager
 from playwright.sync_api._generated import Page
 from playwright.sync_api import (
     Frame,
-    Browser,
     BrowserContext,
-    Playwright,
     Response as SyncPlaywrightResponse,
 )
 from playwright.async_api._generated import Page as AsyncPage
 from playwright.async_api import (
     Frame as AsyncFrame,
-    Browser as AsyncBrowser,
-    Playwright as AsyncPlaywright,
     Response as AsyncPlaywrightResponse,
     BrowserContext as AsyncBrowserContext,
 )
@@ -37,6 +33,7 @@ from scrapling.core._types import (
     Optional,
     Callable,
     TYPE_CHECKING,
+    cast,
     overload,
     Tuple,
     ProxyType,
@@ -61,12 +58,12 @@ class SyncSession:
         self.max_pages = max_pages
         self.page_pool = PagePool(max_pages)
         self._max_wait_for_page = 60
-        self.playwright: Playwright | Any = None
-        self.context: BrowserContext | Any = None
-        self.browser: Optional[Browser] = None
+        self.playwright: Any = None
+        self.context: Any = None
+        self.browser: Any = None
         self._is_alive = False
 
-    def start(self):
+    def start(self) -> None:
         pass
 
     def close(self):  # pragma: no cover
@@ -215,13 +212,13 @@ class AsyncSession:
         self.max_pages = max_pages
         self.page_pool = PagePool(max_pages)
         self._max_wait_for_page = 60
-        self.playwright: AsyncPlaywright | Any = None
-        self.context: AsyncBrowserContext | Any = None
-        self.browser: Optional[AsyncBrowser] = None
+        self.playwright: Any = None
+        self.context: Any = None
+        self.browser: Any = None
         self._is_alive = False
         self._lock = Lock()
 
-    async def start(self):
+    async def start(self) -> None:
         pass
 
     async def close(self):
@@ -378,6 +375,8 @@ class AsyncSession:
 
 
 class BaseSessionMixin:
+    _config: "PlaywrightConfig | StealthConfig"
+
     @overload
     def __validate_routine__(self, params: Dict, model: type[StealthConfig]) -> StealthConfig: ...
 
@@ -404,7 +403,7 @@ class BaseSessionMixin:
         return config
 
     def __generate_options__(self, extra_flags: Tuple | None = None) -> None:
-        config: PlaywrightConfig | StealthConfig = self._config  # type: ignore[has-type]
+        config: PlaywrightConfig | StealthConfig = self._config
         self._context_options.update(
             {
                 "proxy": config.proxy,
@@ -466,7 +465,7 @@ class DynamicSessionMixin(BaseSessionMixin):
 
 class StealthySessionMixin(BaseSessionMixin):
     def __validate__(self, **params):
-        self._config: StealthConfig = self.__validate_routine__(params, model=StealthConfig)
+        self._config = self.__validate_routine__(params, model=StealthConfig)
         self._context_options.update(
             {
                 "is_mobile": False,
@@ -482,22 +481,23 @@ class StealthySessionMixin(BaseSessionMixin):
         self.__generate_stealth_options()
 
     def __generate_stealth_options(self) -> None:
-        flags = tuple()
-        if not self._config.cdp_url:
+        config = cast(StealthConfig, self._config)
+        flags: Tuple[str, ...] = tuple()
+        if not config.cdp_url:
             flags = DEFAULT_FLAGS + DEFAULT_STEALTH_FLAGS
 
-            if self._config.block_webrtc:
+            if config.block_webrtc:
                 flags += (
                     "--webrtc-ip-handling-policy=disable_non_proxied_udp",
                     "--force-webrtc-ip-handling-policy",  # Ensures the policy is enforced
                 )
-            if not self._config.allow_webgl:
+            if not config.allow_webgl:
                 flags += (
                     "--disable-webgl",
                     "--disable-webgl-image-chromium",
                     "--disable-webgl2",
                 )
-            if self._config.hide_canvas:
+            if config.hide_canvas:
                 flags += ("--fingerprinting-canvas-image-data-noise",)
 
         super(StealthySessionMixin, self).__generate_options__(flags)