storage: multi-storage management with per-storage quota

Replace the single fixed /records path with a list of storages and an
active selection (where new recordings go). Quota is now per-storage.

- config: StorageItem(id,name,type,path,quota_gb,nas-meta) + Storage keeps
  global retention_days/segment_seconds; active + items. Migration from the
  old single {path,quota_gb} schema → one local item.
- recorder: write to the active storage; restart_all() repoints on switch;
  NAS-not-mounted guard (never write into the container overlay).
- indexer: scan ALL storage roots so recordings survive an active switch.
- retention: enforce quota PER storage via db.total_size_under /
  oldest_recordings_under (path-prefix LIKE).
- api/storages: GET/POST/PUT/DELETE + activate + policy. NAS uses host-mount
  (backend stores SMB params, generates the mount/fstab command, reports
  ismount status). Retire old POST /api/storage.
- frontend: new "Хранилища" settings tab — table with inline per-row quota,
  add form (local folder / NAS SMB), global policy (segment + retention).
- compose: add shared ./storages:/storages root for extra local folders and
  host-mounted NAS shares.

VERSION 0.0.127.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/app/db.py

@@ -8,6 +8,14 @@ import aiosqlite
 
 from .models import Recording
 
+
+def _like_prefix(prefix: str) -> str:
+    """LIKE-шаблон для путей внутри хранилища: '<path>/%' с экранированием %, _, \\."""
+    p = prefix.rstrip("/") + "/"
+    p = p.replace("\\", "\\\\").replace("%", "\\%").replace("_", "\\_")
+    return p + "%"
+
+
 SCHEMA = """
 CREATE TABLE IF NOT EXISTS recordings (
   id          INTEGER PRIMARY KEY AUTOINCREMENT,
@@ -105,6 +113,24 @@ class Database:
         rows = await cur.fetchall()
         return [Recording(**dict(r)) for r in rows]
 
+    # ── per-storage (по префиксу пути) — для квоты на каждое хранилище ──
+    async def total_size_under(self, prefix: str) -> int:
+        cur = await self.conn.execute(
+            "SELECT COALESCE(SUM(size_bytes), 0) FROM recordings WHERE path LIKE ? ESCAPE '\\'",
+            (_like_prefix(prefix),),
+        )
+        row = await cur.fetchone()
+        return int(row[0]) if row else 0
+
+    async def oldest_recordings_under(self, prefix: str, limit: int = 50) -> list[Recording]:
+        cur = await self.conn.execute(
+            "SELECT * FROM recordings WHERE path LIKE ? ESCAPE '\\' "
+            "ORDER BY started_at ASC LIMIT ?",
+            (_like_prefix(prefix), limit),
+        )
+        rows = await cur.fetchall()
+        return [Recording(**dict(r)) for r in rows]
+
     async def recordings_before(self, ts: int) -> list[Recording]:
         cur = await self.conn.execute(
             "SELECT * FROM recordings WHERE started_at < ? ORDER BY started_at ASC", (ts,)