feat: add get_info tool using SYNO.FileStation.List::getinfo

SYNO.FileStation.Stat is absent from this NAS's API registry.
SYNO.FileStation.List::getinfo returns identical data and is confirmed
working.

- tools/filestation.py: new get_info tool — accepts one or more
  comma-separated paths, calls getinfo with real_path/size/time/perm/
  owner/type additional fields, returns a 9-column table
- tests: 6 new tests covering single file, directory, multi-path,
  empty input, DSM error, and correct API method assertion
- SPEC.md: remove SYNO.FileStation.Stat from API table, rewrite get_info
  tool section to reference getinfo, update list_dir note
- CLAUDE.md: update Implemented Tools list

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -90,6 +90,10 @@ src/mcp_synology_filestation/
 
 ## Implemented Tools
 
-_(none yet — pending implementation approval)_
+| Tool | Description |
+|------|-------------|
+| `list_shares` | List all shared folders with volume usage |
+| `list_dir` | List directory contents with pagination and sorting |
+| `get_info` | Get detailed metadata for one or more paths |
 
 See [SPEC.md](SPEC.md) for the full planned tool set.