feat: #78 Excalidraw finitions + #67 push + #68 health-detailed + #77 desktop jumplist

#78 Excalidraw — finitions B5/C8/F2/F3
- backend/indexer.py: port Python pur de lz-string decompressFromBase64 (bitsPerChar=6, resetValue=32) validé contre 4 fixtures JS truth (texte accentué, edge cases) — remplace le stub base64 non-fonctionnel
- B5 indexation: .excalidraw.md (format plugin Obsidian) maintenant décompressé côté Python → texte indexé pour recherche TF-IDF
- 7 nouveaux tests B5 dans tests/test_excalidraw.py (13/13 total)
- F2: excalidraw-viewer.test.mjs enregistré dans CI (lint job)
- F3: tests/e2e/excalidraw.spec.js (9 specs — ouverture .excalidraw/.excalidraw.md, création via modale/menu contextuel, toolbar, thème, pop-out, recherche)
- Fixtures test_vault/diagram.excalidraw + diagram.excalidraw.md

#67 Push notifications (Web Push API + VAPID)
- backend/push.py: router + VAPID keys + send_push_notification (pywebpush>=2.3.0)
- frontend/js/push.js: subscription UI + service worker integration
- tests/test_push.py: 10 tests (subscribe/list/unsubscribe/vapid key)
- requirements.txt + sw.js + locales push strings

#68 Health check enrichi
- backend/main.py: GET /api/health/detailed (admin) — memory/cpu/disk/backups/index/SSE connections
- backend/indexer.py: _last_full_index_ts tracking
- tests/conftest.py: admin_client fixture
- tests/test_api_main.py: 3 nouveaux tests health detailed

#77 Desktop jumplist
- desktop/src/jumplist.rs: Windows jumplist integration
- Cargo.toml/lock + capabilities + main.rs
- frontend/js/desktop.js: Tauri bridge (isTauriEnv, invoke, getSystemTheme, syncSystemTheme, shouldShowWizard, crash banner)
- tests/frontend/desktop.test.mjs: 21 tests JSDOM (détection, invoke degradation, theme gating, wizard, crash banner)
- tests/frontend/unit.test.mjs: desktop.js whitelisted (standalone global reader)

# Frontend & CI
- frontend/sw.js: réécriture complète (precache + push event handlers + offline)
- frontend/index.html: section push dans settings + about repositionné
- frontend/js/app.js: initDesktopIntegration + initPush
- CI .gitea/workflows/ci.yml: excalidraw-viewer.test.mjs ajouté au lint job

All checks: ruff clean, 552 backend tests pass, 9 frontend unit, 5 excalidraw-viewer, 21 desktop, 9 pane-manager, validate-imports 33 modules.

tests/conftest.py

@@ -1,6 +1,8 @@
 # tests/conftest.py — Shared fixtures for ObsiGate test suite
 import os
 import sys
+import shutil
+import json
 from pathlib import Path
 
 import pytest
@@ -106,7 +108,96 @@ def app_with_vault(test_vault_dir: str):
     return client
 
 
-@pytest.fixture
+@ pytest.fixture
 def client(app_with_vault):
     """Alias for app_with_vault."""
     return app_with_vault
+
+
+@ pytest.fixture
+def admin_client(tmp_path):
+    """TestClient with auth enabled, isolated temp data, admin user provisioned.
+    
+    Used by tests that need admin authentication (e.g., /api/health/detailed).
+    """
+    data_dir = tmp_path / "data"
+    data_dir.mkdir()
+
+    import json
+    from backend.auth.password import hash_password
+
+    pw_hash = hash_password("chab30")
+    users = {
+        "version": 1,
+        "users": {
+            "admin": {
+                "id": "admin-1",
+                "username": "admin",
+                "display_name": "admin",
+                "password_hash": pw_hash,
+                "role": "admin",
+                "vaults": ["*"],
+                "active": True,
+                "created_at": "2026-01-01T00:00:00",
+            },
+            "normaluser": {
+                "id": "user-1",
+                "username": "normaluser",
+                "display_name": "normal",
+                "password_hash": hash_password("normal123"),
+                "role": "user",
+                "vaults": ["TestVault"],
+                "active": True,
+                "created_at": "2026-01-01T00:00:00",
+            },
+        },
+    }
+    (data_dir / "users.json").write_text(json.dumps(users), encoding="utf-8")
+
+    src_secret = Path("data/secret.key")
+    if src_secret.exists():
+        shutil.copy2(str(src_secret), str(data_dir / "secret.key"))
+
+    orig_cwd = os.getcwd()
+    test_vault_path = os.path.abspath("test-vault")
+    os.chdir(str(tmp_path))
+
+    os.environ["VAULT_1_NAME"] = "TestVault"
+    os.environ["VAULT_1_PATH"] = test_vault_path
+    os.environ["OBSIGATE_AUTH_ENABLED"] = "true"
+    os.environ["OBSIGATE_ADMIN_USER"] = "admin"
+    os.environ["OBSIGATE_ADMIN_PASSWORD"] = "chab30"
+    os.environ["OBSIGATE_WATCHER_ENABLED"] = "false"
+
+    import backend.main
+    backend.main._load_config = lambda: {"watcher_enabled": False}
+
+    from backend.main import app
+    from backend.indexer import build_index, index
+    import asyncio
+
+    for key in list(index.keys()):
+        del index[key]
+
+    loop = asyncio.new_event_loop()
+    asyncio.set_event_loop(loop)
+    loop.run_until_complete(build_index())
+
+    from backend.search import init_inverted_index
+    init_inverted_index()
+
+    from fastapi.testclient import TestClient
+    client = TestClient(app)
+    yield client
+
+    if hasattr(client, "close"):
+        client.close()
+    loop.run_until_complete(asyncio.sleep(0))
+
+    os.chdir(orig_cwd)
+    shutil.rmtree(str(tmp_path), ignore_errors=True)
+    for k in [
+        "VAULT_1_NAME", "VAULT_1_PATH", "OBSIGATE_AUTH_ENABLED",
+        "OBSIGATE_ADMIN_USER", "OBSIGATE_ADMIN_PASSWORD", "OBSIGATE_WATCHER_ENABLED",
+    ]:
+        os.environ.pop(k, None)