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)

frontend/assets/sources.js

@@ -0,0 +1,69 @@
+/* Brain of Reese — Sources page (knowledge base index view).
+ * Scaffolding-stage: fetches /api/docs (implemented in the import phase);
+ * until then it renders the empty state.
+ */
+
+const tbody = document.querySelector("#docs-tbody");
+const emptyEl = document.querySelector("#sources-empty");
+const tableWrap = document.querySelector(".table-wrap");
+const statDocs = document.querySelector("#stat-docs");
+const statChunks = document.querySelector("#stat-chunks");
+const statLast = document.querySelector("#stat-last");
+
+function fmtDate(iso) {
+  try {
+    return new Date(iso).toLocaleString();
+  } catch {
+    return iso;
+  }
+}
+
+async function loadDocs() {
+  let r;
+  try {
+    r = await fetch("/api/docs");
+  } catch {
+    showEmpty();
+    return;
+  }
+  if (!r.ok) {
+    showEmpty();
+    return;
+  }
+  const { documents } = await r.json();
+  if (!documents.length) {
+    showEmpty();
+    return;
+  }
+
+  tbody.innerHTML = "";
+  let totalChunks = 0;
+  let last = "";
+  for (const d of documents) {
+    totalChunks += d.chunks;
+    if (d.indexed_at > last) last = d.indexed_at;
+    const tr = document.createElement("tr");
+    tr.innerHTML = `
+      <td>${d.source}</td>
+      <td title="${d.path}">${d.path}</td>
+      <td>${d.title}</td>
+      <td>${d.chunks}</td>
+      <td>${fmtDate(d.indexed_at)}</td>`;
+    tbody.appendChild(tr);
+  }
+  statDocs.textContent = String(documents.length);
+  statChunks.textContent = String(totalChunks);
+  statLast.textContent = last ? fmtDate(last) : "–";
+  emptyEl.hidden = true;
+  tableWrap.hidden = false;
+}
+
+function showEmpty() {
+  statDocs.textContent = "0";
+  statChunks.textContent = "0";
+  statLast.textContent = "–";
+  emptyEl.hidden = false;
+  if (tableWrap) tableWrap.hidden = true;
+}
+
+loadDocs();