feat(rules): project rule + topic suppressions

Lets a project mute individual rules or whole topics from rulebooks it
subscribes to, without unsubscribing the rulebook. Two new association
tables (migration 0060), 4 MCP tools (suppress/unsuppress × rule/topic),
4 REST endpoints, and an inline "× skip" affordance plus collapsed
"Suppressed (N)" section in the project's Rules tab.

get_applicable_rules now emits suppressed_rules and suppressed_topics
(detail objects with rulebook/topic context, not just IDs) so the UI
can render the suppressed list without a follow-up lookup. The main
rules projection grew topic_id and rulebook_id columns for the per-row
suppress affordance.

Project deletion cascades the suppression rows via hard DELETE — they
are pure associations with no soft-delete column, and restoring a
deleted project should start fresh, not inherit stale mutes.

Project-scoped rules (Rule.project_id) are deliberately not suppressible
— delete them with delete_rule instead.

Implements plan-task #187.

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

src/fabledassistant/models/rulebook.py

@@ -131,3 +131,22 @@ project_rulebook_subscriptions = Table(
     Column("rulebook_id", BigInteger, ForeignKey("rulebooks.id", ondelete="CASCADE"), primary_key=True),
     Column("created_at", DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)),
 )
+
+# Suppressions — let a project mute individual rules or whole topics from
+# rulebooks it subscribes to, without unsubscribing the rulebook itself.
+# FKs CASCADE so the row vanishes when its parent is removed.
+project_rule_suppressions = Table(
+    "project_rule_suppressions",
+    Base.metadata,
+    Column("project_id", BigInteger, ForeignKey("projects.id", ondelete="CASCADE"), primary_key=True),
+    Column("rule_id", BigInteger, ForeignKey("rules.id", ondelete="CASCADE"), primary_key=True),
+    Column("created_at", DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)),
+)
+
+project_topic_suppressions = Table(
+    "project_topic_suppressions",
+    Base.metadata,
+    Column("project_id", BigInteger, ForeignKey("projects.id", ondelete="CASCADE"), primary_key=True),
+    Column("topic_id", BigInteger, ForeignKey("rulebook_topics.id", ondelete="CASCADE"), primary_key=True),
+    Column("created_at", DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)),
+)