E2E sub-agent finding: register a materialized BQ row → sync to materialize
the parquet at `/data/extracts/bigquery/data/<id>.parquet` → DELETE the
registry row. The DB row goes away but:
- the parquet file stays on disk forever, AND
- the sync_state row stays, so `/api/sync/manifest` keeps advertising the
dropped table to `da sync`, AND
- the orchestrator's next rebuild can resurrect a master view by picking
up the leftover parquet.
Two-part fix in `unregister_table`:
1. For materialized rows on bigquery/keboola, remove
`${DATA_DIR}/extracts/<source_type>/data/<name>.parquet` (and any stale
`<name>.parquet.tmp` from a crashed prior materialize). Filename is
keyed on `table_registry.name` to match sync_state bookkeeping.
File-removal errors are logged but don't fail the DELETE — the registry
row is already gone, and an orphan parquet won't get a master view at
next rebuild because the orchestrator's _meta-driven scan never picks
up bare parquet files.
2. Always clear `sync_state` + `sync_history` rows for the dropped table_id
so the manifest stops advertising the table — applies to all source
types and modes, not just materialized, since any synced row had a
sync_state entry.
Orchestrator-side defensive guard (Finding 2b) is a no-op in the current
implementation: `_attach_and_create_views` only creates master views from
`_meta` rows in each connector's `extract.duckdb`, so a parquet without a
matching `_meta` entry is already invisible to the rebuild. The new
test `test_orchestrator_skips_orphan_parquet_in_extracts` is kept as a
regression guard for that contract.
5 tests cover: BQ + Keboola materialized DELETE removes parquet, remote
DELETE doesn't error trying to remove a non-existent file, sync_state
cleared on DELETE, orchestrator orphan-skip invariant.
