Add KB Capture v2 - clip-based recording system

New features:
- Clip-based workflow: record short clips, keep or delete
- Toggle recording with Ctrl+Shift+R
- Session management (start, clips, end)
- Modern CustomTkinter GUI with dark theme
- Global hotkeys for hands-free control
- Whisper transcription (local, no API)
- FFmpeg screen + audio capture
- Export to clawdbot_export/ for Mario processing

Files added:
- recorder.py: FFmpeg screen recording
- session.py: Session/clip management
- hotkeys.py: Global hotkey registration
- kb_capture.py: Main application logic
- gui_capture.py: Modern GUI
- export.py: Merge clips, transcribe, export

Docs:
- docs/KB-CAPTURE.md: Full documentation

Entry point: uv run kb-capture

pyproject.toml

@@ -41,6 +41,11 @@ dev = [
 gui = [
     "customtkinter>=5.2.0",
 ]
+capture = [
+    "customtkinter>=5.2.0",
+    "keyboard>=0.13.5",  # Global hotkeys
+    "pystray>=0.19.0",   # System tray (optional)
+]
 pdf = [
     "pandoc",  # For PDF generation fallback
 ]
@@ -48,6 +53,7 @@ pdf = [
 [project.scripts]
 cad-doc = "cad_documenter.cli:main"
 cad-doc-gui = "cad_documenter.gui:main"
+kb-capture = "cad_documenter.gui_capture:main"
 
 [project.urls]
 Homepage = "http://100.80.199.40:3000/Antoine/CAD-Documenter"