Add sync recovery commands for interrupted syncs

- Add wp mls recovery list to show resumable syncs
- Add wp mls recovery auto to auto-resume most recent failed sync
- Add wp mls recovery cleanup to mark stale syncs (>1hr) as failed
- Track last_next_link during incremental sync pagination
- Add get_resumable_syncs(), cleanup_stale_syncs(), auto_resume() methods

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

wp-content/plugins/mls-by-hansonxyz/docs/CLAUDE.md

@@ -76,6 +76,11 @@ wp mls cache cleanup
 wp mls cache missing              # View failed media downloads
 wp mls cache missing --limit=20   # View first 20 entries
 wp mls cache missing --clear      # Clear the log
+
+# Recovery commands
+wp mls recovery list              # Show resumable syncs
+wp mls recovery auto              # Auto-resume most recent failed sync
+wp mls recovery cleanup           # Mark stale (>1hr) syncs as failed
 ```
 
 ### Progress Output
@@ -100,6 +105,22 @@ Format: `[timestamp] listing_key | media_key | error | url`
 
 Media downloads use exponential backoff (1s, 2s, 4s, 8s, 16s) for rate limit (429) and server errors (5xx).
 
+### Sync Recovery
+
+The sync engine saves progress after each page, allowing interrupted syncs to resume:
+
+1. **Automatic state tracking**: `last_next_link` saved after each API page
+2. **Stale sync detection**: Syncs running >1 hour marked as failed
+3. **Resume commands**:
+   - `wp mls sync resume --id=<ID>` - Resume specific sync
+   - `wp mls recovery auto` - Auto-resume most recent failed sync
+   - `wp mls recovery list` - View all resumable syncs
+
+For cron jobs, consider adding recovery at the start:
+```bash
+wp mls recovery auto --quiet && wp mls sync incremental
+```
+
 ### Public API Functions
 
 Available for themes/plugins: