feat(organize/scan): transfer modes, seeding-safe relocation, inode dedup, incremental scanning

- Organizer: add move/copy/hardlink/symlink transfer modes (default move),
  per-request target_path/transfer_mode overrides, and honor organize.target_dir
  / organize.transfer_mode settings.
- keep_seeding (default on): escalate move->hardlink (cross-device->copy) so the
  qBittorrent source stays in place and continues seeding after organize.
- qBittorrent SetLocation + POST /downloads/relocate to migrate whole torrents
  while keeping them seeding.
- Scanner: FileID (device:inode) hardlink dedup to avoid duplicate recognition
  and double-counted storage; extract single-file ingest.
- Watcher: recursive watch + incremental per-file ingest/remove instead of full
  re-scan; periodic full library scan now gated behind scan.periodic_enabled
  (default off) to reduce disk wear.
- Telegram bot: handle callback_query in polling, declare allowed_updates in
  webhook, answer callbacks.
- Frontend: settings for transfer mode / keep_seeding / periodic scan; organize
  panel target dir + transfer mode overrides.
- Tests for transfer modes, organizer resolution, SetLocation, inode dedup,
  incremental ingest/remove.

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

internal/model/model.go

@@ -96,6 +96,12 @@ type Media struct {
 	// Computed on-demand by the duplicate finder; format: "<hex>-<size>".
 	FileHash string `gorm:"index;size:64" json:"file_hash,omitempty"`
 
+	// FileID is a "device:inode" identity for the underlying file. Hardlinks
+	// to the same data share a FileID, letting the scanner skip re-importing a
+	// seeding source kept by keep_seeding and its organized hardlink as two
+	// separate items (avoids duplicate rows + double-counted storage).
+	FileID string `gorm:"index;size:64" json:"file_id,omitempty"`
+
 	// IsDuplicate flags this media as a duplicate of another media row.
 	IsDuplicate bool   `gorm:"default:false" json:"is_duplicate"`
 	DuplicateOf string `gorm:"size:36" json:"duplicate_of,omitempty"`