Implementation spec: governance, decision intelligence, theme system, and E2E bug fixes

Implements the 2026-04-02 transformation spec (Phases 1-8) and fixes all
critical bugs found during 5-pipeline E2E testing.

Governance & Decision Intelligence:
- Pipeline-specific stage order in checkpoint (replaces global STAGES list)
- Provider scoring engine (lib/scoring.py) with 7-dimension weighted ranking
- Decision log artifact enforced at proposal/idea stage across all 10 pipelines
- Delivery promise classifier prevents silent motion-to-still downgrades
- Structured shot language in scene_plan schema (camera, lens, lighting, DOF)
- Variation checker and slideshow risk scorer block samey output before render
- Creative intake, capability extension, and creative-intake meta skills
- Final self-review artifact with 5 mandatory checks before presenting output
- Source media review contract for user-supplied footage

Render & Theme System:
- Remotion AnimatedBackground now derives colors from playbook (no more hardcoded
  dark blue fintech gradient on every video)
- video_compose builds custom ThemeConfig from playbook YAML colors/fonts —
  custom playbooks flow through to Remotion automatically
- Explainer component wires theme to all child components (charts, cards, etc.)
- resolveAsset() handles absolute paths on Windows/Unix via file:// URIs
- RENDERER_FAMILY_MAP synced with actual Remotion compositions

Critical Bug Fixes:
- Windows npx subprocess: run_command() resolves .cmd wrappers via shutil.which()
- Silent renderer downgrade: Remotion failure now returns explicit error with
  options instead of silently falling back to FFmpeg
- .env inline comment parsing strips trailing # comments from API keys
- concat_path UnboundLocalError in video_compose finally block
- audio_mixer and showcase_card capture=True kwarg bug
- Selector estimate_cost() calls fixed (_select_tool -> _select_best_tool)
- asset_manifest schema expanded with provider, license, subtype fields
- screen-demo subtitle_gen moved from required to optional tools
- Duration drift detection in post-render final review (>25% warns)

tools/base_tool.py

@@ -10,6 +10,7 @@ import hashlib
 import inspect
 import json
 import os
+import platform
 import subprocess
 import shutil
 from abc import ABC, abstractmethod
@@ -37,6 +38,12 @@ def _load_dotenv() -> None:
             key, _, value = line.partition("=")
             key = key.strip()
             value = value.strip().strip("'\"")
+            # Strip inline comments: VAR=value  # comment
+            # But only if the # is preceded by whitespace (avoid stripping from values like colors)
+            if "  #" in value:
+                value = value[:value.index("  #")].rstrip()
+            elif "\t#" in value:
+                value = value[:value.index("\t#")].rstrip()
             if key and key not in os.environ:
                 os.environ[key] = value
 
@@ -294,9 +301,18 @@ class BaseTool(ABC):
         timeout: Optional[int] = None,
         cwd: Optional[Path] = None,
     ) -> subprocess.CompletedProcess:
-        """Run a subprocess command with standard error handling."""
+        """Run a subprocess command with standard error handling.
+
+        On Windows, resolves .cmd/.bat wrappers (e.g. npx, npm) via
+        shutil.which() so subprocess.run() can find them without shell=True.
+        """
+        resolved_cmd = list(cmd)
+        if platform.system() == "Windows" and resolved_cmd:
+            exe = shutil.which(resolved_cmd[0])
+            if exe:
+                resolved_cmd[0] = exe
         return subprocess.run(
-            cmd,
+            resolved_cmd,
             capture_output=True,
             text=True,
             timeout=timeout,