P4 complete: OAuth authorization-code flow, MCP-OAuth, AddApps connects

- migration 0005 oauth_states: one-time states (10-min TTL), consumed by a
  CAS DELETE on callback — replays and forgeries both 404
- POST /api/apps/oauth/start: OIDC discovery on the configured issuer (or
  the custom MCP issuer for authType=mcp_oauth), state row, authorize URL
- GET /api/apps/oauth/callback: code exchanged at the REAL token endpoint
  (client id+secret form POST); the access token goes straight to the
  broker (test proves it never appears unencrypted in Postgres); connection
  row + audit; redirects to the claw's Add Apps panel
- [oauth] config (issuer/client/redirect_base) wired through AppState
- Tests against a real local IdP server (discovery + validating token
  endpoint): full round trip, broker-held token, replay/forged state
  refused, bad code fails exchange, mcp_oauth uses the custom issuer while
  plain oauth refuses without a configured IdP
- AddAppsApp: live connection badges + inline API-key connect per app
  (E2E: connect Notion by key from the directory)

136 Rust + 63 frontend tests + 21 Playwright journeys.

Co-Authored-By: Claude Fable 5 <[email protected]>

.sqlx/query-b53b31468a210a8055710c4f17c41b66cf409b3299f32bc00e3beb164f58f4e7.json

@@ -0,0 +1,20 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "INSERT INTO oauth_states\n            (state, workspace_id, user_id, agent_id, provider, auth_type,\n             issuer_url, expires_at)\n         VALUES ($1, $2, $3, $4, $5, $6, $7, now() + interval '10 minutes')",
+  "describe": {
+    "columns": [],
+    "parameters": {
+      "Left": [
+        "Text",
+        "Uuid",
+        "Uuid",
+        "Uuid",
+        "Text",
+        "Text",
+        "Text"
+      ]
+    },
+    "nullable": []
+  },
+  "hash": "b53b31468a210a8055710c4f17c41b66cf409b3299f32bc00e3beb164f58f4e7"
+}