perf: optimize MCP server (O(1) auth, compact JSON, trashedAt fix) + memento-note performance (lazy loading, server-side filtering, XSS fixes, dead code removal, security hardening)

MCP Server:
- Fix validateApiKey: O(1) direct lookup by shortId instead of loading all keys
- Add trashedAt:null filter to ALL note queries (trashed notes leaked in results)
- Compact JSON output (~40% smaller responses)
- Bounded session cache (Map with MAX_SESSIONS=500) to prevent memory leaks
- PostgreSQL connection pooling (connection_limit=10)
- Rewrite all 22 tool descriptions in clear English
- Fix /sse fallback to proper 307 redirect

memento-note Performance:
- loading=lazy on all note images
- Split notebooksRefreshKey from global refreshKey (note CRUD no longer re-fetches notebooks)
- Remove searchKey from trash count deps (no re-fetch on every keystroke)
- Server-side notebookId filter in getAllNotes() (biggest win)
- Skip collaborator fetch for non-shared notes (eliminates N+1 API calls)
- next/dynamic for MarkdownContent + 4 modals (code-split remark/rehype/KaTeX)
- Memoize DOMPurify sanitize with useMemo

Security:
- XSS: DOMPurify sanitize in note-card and note-history-modal
- Auth anti-enumeration: uniform errors in auth.ts
- CRON_SECRET mandatory on cron endpoints
- Rate limiting on login (5 attempts/min per email)
- Centralized API auth helpers (requireAuth/requireAdmin)
- randomize-labels changed GET→POST
- Removed debug endpoints (/api/debug/config, /api/debug/test-chat)

Cleanup:
- Removed dead code: .backup-keep, settings-backup, fix-*.js, debug-theme, fix-labels route
- Removed sensitive console.error in auth.ts
- Ollama fetchWithTimeout (30s/60s AbortController)
- i18n: full Arabic translation, Farsi missing keys
- Masonry drag-and-drop fix (localOrderMap, cross-section block)
- Sidebar notebook tooltip on truncation

mcp-server/node_modules/.package-lock.json

@@ -848,20 +848,6 @@
         "node": ">= 0.6"
       }
     },
-    "node_modules/fsevents": {
-      "version": "2.3.3",
-      "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.3.3.tgz",
-      "integrity": "sha512-5xoDfX+fL7faATnagmWPpbFtwh/R77WmMMqqHGS65C3vvB0YHrgF+B1YmZ3441tMj5n63k0212XNoJwzlhffQw==",
-      "hasInstallScript": true,
-      "license": "MIT",
-      "optional": true,
-      "os": [
-        "darwin"
-      ],
-      "engines": {
-        "node": "^8.16.0 || ^10.6.0 || >=11.0.0"
-      }
-    },
     "node_modules/function-bind": {
       "version": "1.1.2",
       "resolved": "https://registry.npmjs.org/function-bind/-/function-bind-1.1.2.tgz",