Phase 6: HITL review endpoints + audit trail

- New job_corrections table (append-only audit log) + migration
- Add approved / reviewed_by / reviewed_at columns to jobs
- PATCH  /documents/{id}         apply field-level corrections
- GET    /documents/{id}/history return chronological audit trail
- POST   /documents/{id}/approve lock final version (idempotent)
- Dotted field-path applier with root allow-list + list-index support
- Auto-clear `missing_field` review flag when required header keys filled
- Atomic batch apply: malformed path in batch rolls back all changes
- 22 new tests (11 repository-level, 11 API-level); 184 total passing

Co-Authored-By: adrian kuman firmansah <adriancuman@gmail.com>

src/ocr_sprint/schemas/document.py

@@ -55,3 +55,7 @@ class DocumentResponse(BaseModel):
     data: ExtractionResult | None = None
     review_flags: list[str] = Field(default_factory=list)
     error: str | None = None
+    # Phase 6 — HITL review state.
+    approved: bool = False
+    reviewed_by: str | None = None
+    reviewed_at: datetime | None = None