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/_controllers.py

@@ -8,11 +8,10 @@ from playwright.sync_api import (
 from playwright.async_api import (
     async_playwright,
     Locator as AsyncLocator,
-    BrowserContext as AsyncBrowserContext,
 )
 
 from scrapling.core.utils import log
-from scrapling.core._types import Unpack
+from scrapling.core._types import Optional, ProxyType, Unpack
 from scrapling.engines.toolbelt.proxy_rotation import is_proxy_error
 from scrapling.engines.toolbelt.convertor import Response, ResponseFactory
 from scrapling.engines.toolbelt.fingerprints import generate_convincing_referer
@@ -134,6 +133,7 @@ class DynamicSession(SyncSession, DynamicSessionMixin):
         )
 
         for attempt in range(self._config.retries):
+            proxy: Optional[ProxyType] = None
             if self._config.proxy_rotator and static_proxy is None:
                 proxy = self._config.proxy_rotator.get_proxy()
             else:
@@ -238,7 +238,7 @@ class AsyncDynamicSession(AsyncSession, DynamicSessionMixin):
         self.__validate__(**kwargs)
         super().__init__(max_pages=self._config.max_pages)
 
-    async def start(self):
+    async def start(self) -> None:
         """Create a browser for this instance and context."""
         if not self.playwright:
             self.playwright = await async_playwright().start()
@@ -246,16 +246,14 @@ class AsyncDynamicSession(AsyncSession, DynamicSessionMixin):
                 if self._config.cdp_url:
                     self.browser = await self.playwright.chromium.connect_over_cdp(endpoint_url=self._config.cdp_url)
                     if not self._config.proxy_rotator and self.browser:
-                        self.context: AsyncBrowserContext = await self.browser.new_context(**self._context_options)
+                        self.context = await self.browser.new_context(**self._context_options)
                 elif self._config.proxy_rotator:
                     self.browser = await self.playwright.chromium.launch(**self._browser_options)
                 else:
                     persistent_options = (
                         self._browser_options | self._context_options | {"user_data_dir": self._user_data_dir}
                     )
-                    self.context: AsyncBrowserContext = await self.playwright.chromium.launch_persistent_context(
-                        **persistent_options
-                    )
+                    self.context = await self.playwright.chromium.launch_persistent_context(**persistent_options)
 
                 if self.context:
                     self.context = await self._initialize_context(self._config, self.context)
@@ -304,6 +302,7 @@ class AsyncDynamicSession(AsyncSession, DynamicSessionMixin):
         )
 
         for attempt in range(self._config.retries):
+            proxy: Optional[ProxyType] = None
             if self._config.proxy_rotator and static_proxy is None:
                 proxy = self._config.proxy_rotator.get_proxy()
             else: