Add Command Center web UI (no build step)

Static HTML/CSS/JS served by FastAPI (mounted at /ui, / redirects there),
talking to the existing JSON API — no node/npm, no bundler.

- games/versions sidebar with A/B version selectors
- visual 4-axis diff (types/methods/events/fields, +/- struct_layout) with
  +/-/~ rows, per-axis counts, class (owner) filter, moved-methods section
- single-snapshot browser (tabs + live filter)
- app.py mounts StaticFiles(html=True) last so API routes win; / -> /ui/

Smoke-tested live on uvicorn: /, /ui/ and assets serve 200; UI wiring drives
the same /games and /diff endpoints verified end-to-end. app.js passes
`node --check`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ams/api/app.py

@@ -7,12 +7,18 @@ Run with uvicorn's factory mode (no import-time DB side effects):
 
 from __future__ import annotations
 
+from pathlib import Path
+
 from fastapi import FastAPI
+from fastapi.responses import RedirectResponse
+from fastapi.staticfiles import StaticFiles
 
 from .. import __version__
 from .db import configure, init_db
 from .routes import diff, games, snapshots
 
+_STATIC = Path(__file__).parent / "static"
+
 
 def create_app(database_url: str | None = None) -> FastAPI:
     configure(database_url)
@@ -27,4 +33,11 @@ def create_app(database_url: str | None = None) -> FastAPI:
     def health() -> dict[str, str]:
         return {"status": "ok", "version": __version__}
 
+    @app.get("/", include_in_schema=False)
+    def root() -> RedirectResponse:
+        return RedirectResponse("/ui/")
+
+    # The command-center UI (static HTML/CSS/JS, no build step) is served last so API
+    # routes take precedence.
+    app.mount("/ui", StaticFiles(directory=str(_STATIC), html=True), name="ui")
     return app