feat(admin-api): add single-table restore endpoint

[shiyasmohd]

Summary

• Add POST /datasets/{namespace}/{name}/versions/{revision}/tables/{table_name}/restore endpoint for restoring a single table.
• Support two restore modes: discover latest revision from object storage (UUID heuristic), or activate a specific revision by location_id
• Extend ampctl dataset restore CLI with --table and --location-id flags
• Add integration tests
• Add docs

CLI usage

# Discover latest revision from storage
ampctl dataset restore my_ns/my_dataset@1.0.0 --table blocks

# Activate a specific revision
ampctl dataset restore my_ns/my_dataset@1.0.0 --table blocks --location-id 42