inbound-antispam-panel: migration 0002, journal and filter-list tables

Step 2/12 of docs/plans/inbound-antispam-panel.md, the first migration
after the 2.0 baseline (2.0.1 was cut before it, as agreed).

0002_inbound_spam_log.sql adds inbound_spam_log (one row per recipient:
domain, client IP, envelope, subject, decision, engine, detail) with
indexes on created_at and (inbound_domain, created_at), and
inbound_spam_list (allow / deny entries, unique per list). DDL only;
decision, engine, list_type and entry_type carry CHECKs, as the
baseline does for its own enumerations. Nothing reads or writes the
tables yet.

Tests: TestBaselineSchema pins both tables and user_version 2;
TestOpenMigratesA20Database opens a file holding the baseline alone and
finds its user kept; TestInboundSpamConstraints.

go test ./internal/store/ ok; go vet ./... ok.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/plans/inbound-antispam-panel.md

@@ -243,7 +243,7 @@ Target version cut: **`2.1.0`** (MINOR), after `2.0.0`. One commit per step;
 [development.md](../development.md) § Plan checklists.
 
 - [x] Agree journal fields, retention, and RBAC (this plan § Decisions) — **Composer**
-- [ ] Migration `0002_inbound_spam_log.sql` on the 2.0 baseline — **Composer**
+- [x] Migration `0002_inbound_spam_log.sql` on the 2.0 baseline — **Composer**
 - [ ] Inbound journal-milter + Postfix wiring — **Composer**
 - [ ] mail.log tailer: inbound reject rows — **Composer**
 - [ ] List CRUD + validation + atomic rspamd map sync — **Composer**