feat: scaffold Brain of Reese — FastAPI RAG chat over Postgres 17 + pgvector

Foundation (phase 01, verified):
- FastAPI app: /api/health, /api/suggestions, /api/chat (placeholder),
  static frontend served locally (no CDN)
- Postgres 17 + pgvector via db/Containerfile + compose.yaml
  (podman compose up -d db), Alembic initial migration (documents,
  chunks with vector(768), query_log)
- LLM client targeting https://aipi.reeseapps.com/v1 (turbo/embed);
  scripts/llm_probe.py verified models + 768-dim embeddings live
- Conditional debugpy: imported only when DEBUGPY=1 (attach on demand,
  :5678); logging config for clean single-line logs
- Frontend shell: mobile-first chat + Sources pages, tokens, a11y baselines
- Tests: 24 unit+integration (99% coverage on app/), ruff + pyright clean,
  Playwright smoke E2E (3 tests) against a deterministic mock LLM
- Planning: .agent/PLAN.md (architecture + LOCKED decisions), AGENTS.md,
  6 user stories, 7 phase files (one story / one phase / one Playwright
  suite each)

app/main.py

@@ -0,0 +1,47 @@
+"""Brain of Reese — application entrypoint.
+
+Boots logging + conditional debugpy, then creates the FastAPI app:
+API routes first (so they win over the catch-all), and the static frontend
+mounted last. No CDN: everything the browser needs is served by this
+process from local files (see PLAN §UI/UX — No External Dependencies).
+"""
+from __future__ import annotations
+
+import logging
+from pathlib import Path
+
+from fastapi import FastAPI
+from fastapi.staticfiles import StaticFiles
+
+from app.api.chat import router as chat_router
+from app.api.health import router as health_router
+from app.api.suggestions import router as suggestions_router
+from app.config import get_settings
+from app.core.debugging import configure_debugging
+from app.core.logging import configure_logging
+
+configure_logging()
+configure_debugging()
+
+settings = get_settings()
+logger = logging.getLogger("app")
+
+
+def create_app() -> FastAPI:
+    app = FastAPI(title=settings.app_name, version=settings.app_version)
+
+    # API routes first so they take precedence over the catch-all static mount.
+    app.include_router(health_router, prefix="/api")
+    app.include_router(suggestions_router, prefix="/api")
+    app.include_router(chat_router, prefix="/api")
+
+    static_dir = Path(settings.static_dir).resolve()
+    if static_dir.is_dir():
+        app.mount("/", StaticFiles(directory=static_dir, html=True), name="static")
+    else:
+        logger.warning("static dir %s not found — serving API only", static_dir)
+
+    return app
+
+
+app = create_app()