feat(p0): add favorite folder sync and sqlite data foundation

Implement P0 of the reaction dashboard: config loading with hot reload, SQLite migrations with backups, single-writer queue, read-only Bilibili fav client, folder import/diff sync, invalid-resource handling, blacklist seed, scheduler, and JSON redacted logging. Includes offline unit and transport-level contract tests; all existing and new tests pass.

config.example.json

@@ -0,0 +1,87 @@
+{
+  "mid": 0,
+  "csrf": "从 cookie 中的 bili_jct 取值",
+  "cookie": "粘贴浏览器请求头里的完整 Cookie（需含 SESSDATA、bili_jct、DedeUserID 等）",
+  "overrides": {},
+  "sleep": {
+    "min": 2.5,
+    "max": 7.5,
+    "long_every_min": 20,
+    "long_every_max": 40,
+    "long_min": 30,
+    "long_max": 90,
+    "retry_wait": 45
+  },
+  "telegram": {
+    "enabled": false,
+    "bot_token": "replace-with-telegram-bot-token",
+    "chat_id": 0
+  },
+  "web": {
+    "host": "127.0.0.1",
+    "port": 8080,
+    "auth_token": "replace-with-a-long-random-token",
+    "public_base_url": ""
+  },
+  "storage": {
+    "database_path": "data/app.db",
+    "backup_dir": "data/backup",
+    "backup_keep_days": 14
+  },
+  "folders": [
+    { "year": 2025, "media_id": 4451053851, "title": "咻咻满-reaction-2025" },
+    { "year": 2026, "media_id": 3700023351, "title": "咻咻满 reaction 合集" }
+  ],
+  "track_fans": [37754047],
+  "up_blacklist_seed": [
+    261052419,
+    1908537643,
+    1701121088,
+    542262,
+    376316958,
+    145178393,
+    66389997,
+    293976264,
+    3026109
+  ],
+  "schedule": {
+    "discover_minutes": 60,
+    "folder_sync_minutes": 60,
+    "full_folder_refresh_hours": 6,
+    "snapshot_at": "00:01",
+    "candidate_ttl_days": 7
+  },
+  "notify": {
+    "min_score": 2,
+    "max_items_per_message": 10
+  },
+  "classify": {
+    "require_title": "咻咻满",
+    "positive": [
+      "reaction",
+      "re",
+      "反应",
+      "看",
+      "听",
+      "初听",
+      "首次",
+      "点评",
+      "锐评",
+      "路人",
+      "震惊",
+      "双人"
+    ],
+    "charge": ["充电", "加急", "专场"],
+    "negative": ["歌切", "切片", "纯享", "搬运", "完整版"],
+    "duration_boost": { "gt_30min": 1, "gt_60min": 2 }
+  },
+  "heat_weights": {
+    "view": 0.3,
+    "like": 0.2,
+    "coin": 0.2,
+    "favorite": 0.15,
+    "share": 0.1,
+    "reply": 0.03,
+    "danmaku": 0.02
+  }
+}