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)

tests/e2e/test_smoke.py

@@ -0,0 +1,45 @@
+"""Phase 01 smoke E2E: the app boots, serves the local frontend, and the
+placeholder chat round-trips without a stale button.
+
+Run:  uv run pytest tests/e2e/test_smoke.py -v
+"""
+from __future__ import annotations
+
+import re
+
+import httpx
+from playwright.sync_api import Page, expect
+
+
+def test_health_endpoint(app_url: str) -> None:
+    r = httpx.get(f"{app_url}/api/health", timeout=5)
+    assert r.status_code == 200
+    assert r.json()["status"] == "ok"
+
+
+def test_index_page_loads_locally(page: Page, app_url: str) -> None:
+    page.goto(app_url)
+    assert page.title() == "Brain of Reese"
+    assert page.locator(".brand").is_visible()
+    # No external (CDN) resources in the document.
+    html = page.content()
+    assert 'src="http' not in html
+    assert 'href="http' not in html.replace('href="http://www.w3.org', "")
+
+
+def test_placeholder_chat_roundtrip(page: Page, app_url: str) -> None:
+    page.goto(app_url)
+    page.locator("#message-input").fill("hello brain")
+    page.locator("#send-btn").click()
+
+    # User bubble appears, then the Brain placeholder answer arrives.
+    page.locator(".msg.user .bubble").first.wait_for(state="visible", timeout=10_000)
+    brain_bubble = page.locator(".msg.brain .bubble").first
+    brain_bubble.wait_for(state="visible", timeout=10_000)
+    # to_have_text retries until the async fetch resolves (no stale read).
+    expect(brain_bubble).to_have_text(re.compile("neurons"), timeout=10_000)
+
+    # Button is never left stuck: back to "Send" and enabled.
+    btn = page.locator("#send-btn")
+    assert btn.is_enabled()
+    assert "Send" in btn.inner_text()