chore(deps): re-pin llm-ingestion-okf to v0.3.1 + migrate tests to stable error codes

Pin dae0bd1a -> v0.3.1 (=692f2df) on the public Forgejo mirror; uv.lock pins
the exact commit behind the tag.

- Drop the mypy override: the library ships py.typed from v0.2.0, so strict
  mode now follows its real types instead of follow_untyped_imports.
- Migrate 8 library-error assertions from pytest.raises(match=...) to
  exc.value.code — message text is explicitly unstable from v0.3.0, the
  codes are the stability contract.
- Fix a real breakage the bump surfaced: IngestResult gained a required
  `stamp` field (d3a3bcc), which the delegation fake did not construct.
- The read-only SQL test loses resolution under the code contract
  (`sql_failed` is generic), so it now proves read-onlyness by effect —
  the write never lands — instead of by message wording.
- Correct the guard plan: G1's persist-gate anchor (ingest.py:372-387) died
  with the 2026-07-16 adoption. Door A is ungated by the library's own
  README, so gating stays our responsibility at the call site.

Verified: 426 tests green, golden output byte-exact unchanged, full gate
clean (ruff + format + mypy strict).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RmNAgbRXUgvoSKxVK4Bevv

tests/test_ingest_adoption.py

@@ -53,7 +53,9 @@ class TestDelegation:
         ) -> llm_ingestion_okf.IngestResult:
             calls["args"] = (manifest_path, bundle_dir, ingested_at)
             calls["kwargs"] = kwargs
-            return llm_ingestion_okf.IngestResult(written=(tmp_path / "ingest-e.md",))
+            return llm_ingestion_okf.IngestResult(
+                written=(tmp_path / "ingest-e.md",), stamp="e@0123456789abcdef"
+            )
 
         monkeypatch.setattr(ingest, "materialize_bundle", fake)
         out = ingest.materialize(tmp_path / "manifest.json", tmp_path / "bundle", INGESTED_AT)
@@ -153,6 +155,7 @@ class TestLibraryGuarantees:
         manifest_path = tmp_path / "manifest.json"
         manifest_path.write_text(json.dumps(manifest), encoding="utf-8")
         bundle = tmp_path / "bundle"
-        with pytest.raises(ingest.SourceError, match="returned no columns"):
+        with pytest.raises(ingest.SourceError) as exc:
             ingest.materialize(manifest_path, bundle, INGESTED_AT)
+        assert exc.value.code == "sql_no_columns"
         assert not bundle.exists()