feat: replace GitHub page with embedded Timmy chat interface

Replaces the marketing landing page with a minimal, full-screen chat
interface that connects to a running Timmy instance. Mobile-first design
with single vertical scroll direction, looping scroll, no zoom, no
buttons — just type and press Enter to talk to Timmy.

- docs/index.html: full rewrite as a clean chat UI with dark terminal
  theme, looping infinite scroll, markdown rendering, connection status,
  and /connect, /clear, /help slash commands
- src/dashboard/app.py: add CORS middleware so the GitHub Pages site can
  reach a local Timmy server cross-origin
- src/config.py: add cors_origins setting (defaults to ["*"])

https://claude.ai/code/session_01AWLxg6KDWsfCATiuvsRMGr

src/config.py

@@ -72,6 +72,10 @@ class Settings(BaseSettings):
     # Default is False (telemetry disabled) to align with sovereign AI vision.
     telemetry_enabled: bool = False
 
+    # CORS allowed origins for the web chat interface (GitHub Pages, etc.)
+    # Set CORS_ORIGINS as a comma-separated list, e.g. "http://localhost:3000,https://example.com"
+    cors_origins: list[str] = ["*"]
+
     # Environment mode: development | production
     # In production, security settings are strictly enforced.
     timmy_env: Literal["development", "production"] = "development"