cleanup(phase7): regenerate migrations to post-phase-7 initial (#1666)

* cleanup(phase7): regenerate migrations to post-phase-7 initial

Replace the 32-revision Alembic chain with a single post-Phase-7
initial migration. Fresh empty DB → `alembic upgrade head` now yields
the exact same schema as the current ORM state, with no intermediate
LightRAG / legacy steps.

Ghost-check:
- docs/modularization/cleanup-inventory.md §Phase7-postmerge: chain
  collapsed, zero schema change
- §1 Layer A / B / C untouched: aperag/db/base.py Base.metadata
  unchanged; aperag/db/models.py Invitation class-body `Role` binding
  via `from aperag.domains.identity.db.models import ... Role ...`
  preserved; env.py per-domain model imports preserved
- G17 / G18-alt CRITICAL_WIRINGS unchanged (migration layer doesn't
  touch DI); 20/20 G1-G19 boundary tests pass

Verification:
- Old chain: 32 revisions (base db9c88848f52 → head e1f2a3b4c5d6)
- New chain: 1 revision (base → head 6a8fc31427d9 `post_phase_7_initial`)
- Round-trip: `alembic downgrade base` + `alembic upgrade head`
  succeed against fresh local Postgres 16 + pgvector 0.7.2 DB;
  41 relations created (40 ORM tables + alembic_version)
- Stability: second `alembic revision --autogenerate` produces an
  empty upgrade() / downgrade() (no drift)
- Tables: all 13 domain surfaces present (identity / governance /
  model_platform / marketplace / knowledge_base / indexing /
  retrieval / knowledge_graph / conversation / agent_runtime /
  evaluation) plus 11 legacy local ORMs (ConfigModel / UserQuota /
  Invitation / PromptTemplate / Setting / ExportTask / Evaluation /
  EvaluationItem / Question / QuestionSet / ModelServiceProvider)
- No pgvector extension / Vector column DDL in the initial: no ORM
  declares Vector type post-Phase-7 (LightRAG tables already dropped)
- No re-export shim leakage; invitation.role renders as String(50)
  (EnumColumn helper is a varchar, matching identity domain Role)

Tests:
- tests/unit_test/test_modularization_boundaries.py: 20 passed
- tests/unit_test/ broad regression (minus pre-existing unrelated
  failure `test_phase1_fe_complete_identity_auth_admin_audit_adapter_boundary`):
  577 passed, 29 skipped

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* cleanup(phase7): strip trailing whitespace on new initial migration

Weston blocker-level CR (msg=fa0b6b4e) found 1 mechanical `git diff --check`
blocker: `aperag/migration/versions/20260425041904-6a8fc31427d9.py:4` had
trailing whitespace on the `Revises: ` line (template artifact from alembic
autogenerate). Normalized via `rstrip()` on all lines.

Whitespace-only change; no logic or schema diff.

Ghost-check: none — §1 Layer A/B/C/D/E untouched; whitespace-only trailing-space strip.

---------

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

Author: earayu