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/routes/rulebooks.py

@@ -241,6 +241,54 @@ async def get_project_rules(project_id: int):
     return jsonify(result)
 
 
+@rulebooks_bp.post("/projects/<int:project_id>/suppressions/rules/<int:rule_id>")
+@login_required
+async def suppress_project_rule(project_id: int, rule_id: int):
+    try:
+        await rulebooks_svc.suppress_rule_for_project(
+            project_id=project_id, rule_id=rule_id, user_id=_uid(),
+        )
+    except ValueError as exc:
+        return jsonify({"error": str(exc)}), 404
+    return "", 204
+
+
+@rulebooks_bp.delete("/projects/<int:project_id>/suppressions/rules/<int:rule_id>")
+@login_required
+async def unsuppress_project_rule(project_id: int, rule_id: int):
+    try:
+        await rulebooks_svc.unsuppress_rule_for_project(
+            project_id=project_id, rule_id=rule_id, user_id=_uid(),
+        )
+    except ValueError as exc:
+        return jsonify({"error": str(exc)}), 404
+    return "", 204
+
+
+@rulebooks_bp.post("/projects/<int:project_id>/suppressions/topics/<int:topic_id>")
+@login_required
+async def suppress_project_topic(project_id: int, topic_id: int):
+    try:
+        await rulebooks_svc.suppress_topic_for_project(
+            project_id=project_id, topic_id=topic_id, user_id=_uid(),
+        )
+    except ValueError as exc:
+        return jsonify({"error": str(exc)}), 404
+    return "", 204
+
+
+@rulebooks_bp.delete("/projects/<int:project_id>/suppressions/topics/<int:topic_id>")
+@login_required
+async def unsuppress_project_topic(project_id: int, topic_id: int):
+    try:
+        await rulebooks_svc.unsuppress_topic_for_project(
+            project_id=project_id, topic_id=topic_id, user_id=_uid(),
+        )
+    except ValueError as exc:
+        return jsonify({"error": str(exc)}), 404
+    return "", 204
+
+
 @rulebooks_bp.post("/projects/<int:project_id>/rules")
 @login_required
 async def create_project_rule(project_id: int):