refactor(ingest): adopt shared llm-ingestion-okf v0.3.1 behind a thin adapter

Door A (manifest -> connector -> deterministic materialization -> index) is no
longer implemented here. src/portfolio_optimiser/ingest.py becomes a thin
consumer seam over the shared library, git-pinned to v0.3.1 on the same Forgejo
channel portfolio-optimiser-claude uses. Net -626/+385; ingest.py 599 -> 145 lines.

shared/ingest-spec.md remains the normative spec: the library implements it, it
does not replace it. Spec changes continue to go via commons.

Acceptance criterion met and proven: all three golden bundles (file/sql/http)
are byte-exact before and after, including the idempotence re-run. examples/ and
shared/ carry ZERO modifications -- the fasit was not adjusted to fit.

The rejection set was verified equivalent, not assumed: all 22 malformations the
repo's pydantic models refused are refused by the library, with typed codes
(okf_type_reserved, credential_embedded, extraction_id_duplicate, ...).

Test rebinding (invariants preserved, vehicle changed): the library has zero
runtime dependencies by design, so pydantic is unavailable to it.
ManifestV1.model_validate(dict) -> load_manifest_bytes(bytes); ValidationError ->
ManifestError; model_fields -> dataclasses.fields; PathSecurityError ->
SourceError(path_escape); ValueError -> MaterializationError(ingested_at_invalid).
Tests now also pin the refusal `code`, the library's documented stability
contract -- a sharper assertion than "some validation error was raised".

Two accepted behavioural deltas, recorded rather than silently dropped:
- Title whitespace is stored verbatim instead of collapsed at validation, so the
  frontmatter title and the index label are no longer guaranteed identical for
  irregular whitespace. Both behaviours are spec-conformant (the spec is SILENT;
  the old one was a repo-local pinned decision). Queued as a commons-amendment
  candidate so both stacks pin the same answer. Goldens unaffected.
- The section 8 audit log moves to logger llm_ingestion_okf.materialize. Nothing
  in the repo consumed the old channel.
Also: the `type` discriminator is no longer a dataclass field, so the spec
cross-check asserts it explicitly -- without that line the swap would have
silently narrowed the test.

New tests/test_ingest_library_seam.py pins the seam itself: the restated section 5
stamp formula against the stamp the library actually writes (the one place the
adapter does not purely delegate, since v0.3.1 exposes no stamp helper), the
local-only allow_network default, the list[Path] unwrapping, and a guard that the
adapter never regrows local Door A machinery. All four verified RED when detached,
as were both golden regressions under a byte-level render mutation.

Door A is UNGATED: it calls no guard before writing to disk. Gating untrusted
content remains the caller's responsibility (guard wiring still planned).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01B4jNN186eVqfe1x5DnTU6r

tests/test_ingest_loadbearing.py

@@ -40,7 +40,7 @@ from pathlib import Path
 from typing import Any
 
 import pytest
-from pydantic import ValidationError
+from llm_ingestion_okf import ManifestError
 
 from portfolio_optimiser import okf
 from portfolio_optimiser.ingest import Extraction, materialize
@@ -104,8 +104,9 @@ def test_verdict_typed_manifest_is_rejected_and_writes_nothing(tmp_path: Path) -
     manifest_path = _write_project(tmp_path, extractions)
     bundle_dir = tmp_path / "bundle"
 
-    with pytest.raises(ValidationError):
+    with pytest.raises(ManifestError) as exc:
         materialize(manifest_path, bundle_dir, ingested_at=_INGESTED_AT)
+    assert exc.value.code == "okf_type_reserved"
 
     assert not bundle_dir.exists(), (
         "a verdict-typed manifest must write NOTHING (no index, no files)"