docs(intel): refresh codebase intelligence at 99f59c3 — capture Phase 4 lists + live-sync

Stale intel reflected commit 01f7456 (pre-Phase-4). Refresh adds the shared-lists
+ SSE subsystem: 21 API endpoints (was 10), lists/sse routes, listEmitter/listAccess/rank
libs, PWA lists surface, 7 new arch decisions, and Phase 4 deps (react-router, @dnd-kit,
fractional-indexing). Canonical filenames preserved; API-SURFACE.md + .last-refresh.json regenerated.

.planning/intel/stack.json

@@ -1,11 +1,18 @@
 {
   "_meta": {
-    "updated_at": "2026-06-09T00:00:00Z",
-    "commit": "01f7456b81dd55d477d0bd7530df818f61a873c2",
-    "version": 1
+    "updated_at": "2026-06-09T18:56:37.176Z",
+    "commit": "99f59c3999f4ef992f01ef8f8a38c1d86d2f2a0f",
+    "version": 3
   },
-  "languages": ["TypeScript", "SQL"],
-  "frameworks": ["Hono 4.12.23", "React 19", "Drizzle ORM 0.45.2"],
+  "languages": [
+    "TypeScript",
+    "SQL"
+  ],
+  "frameworks": [
+    "Hono 4.12.23",
+    "React 19",
+    "Drizzle ORM 0.45.2"
+  ],
   "tools": [
     "Vite 8.0.16",
     "vite-plugin-pwa 1.3.0",
@@ -19,12 +26,15 @@
   "package_manager": "pnpm 11.5.1",
   "runtime": "Node.js 22 LTS",
   "database": "MariaDB via mysql2 3.22.4",
-  "cache": "Redis (ioredis — planned for Phase 4 list sync; not yet wired)",
+  "cache": "Redis (ioredis — available in infra; not yet wired; in-memory EventEmitter used for Phase 4 list SSE fan-out)",
   "auth": "Authelia OIDC — authorization_code + PKCE via @hono/oidc-auth 1.8.3",
   "calendar_backend": "Fastmail CalDAV via tsdav 2.2.2 + ical.js 2.2.1",
   "calendar_ui": "@schedule-x/calendar 4.6.0",
   "server_state": "@tanstack/react-query 5.101.0",
   "client_state": "zustand 5.0.14",
+  "routing": "react-router 7.17.0 (BrowserRouter, /calendar + /lists + /lists/:listId)",
+  "drag_and_drop": "@dnd-kit/core 6.3.1 + @dnd-kit/sortable 10.0.0 (list item reorder)",
+  "fractional_rank": "fractional-indexing 3.2.0 (list item ordering — utf8mb4_bin collation in DB)",
   "content_formats": [
     "TypeScript (source)",
     "SQL (Drizzle migrations)",