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/services/trash.py

@@ -55,6 +55,23 @@ async def _cascade(session, user_id: int, etype: str, eid: int, batch: str, now)
         await _set(session, Milestone, [Milestone.user_id == user_id, Milestone.project_id == eid], batch, now)
         # Project-scoped rules cascade with the project they're attached to.
         await _set(session, Rule, [Rule.project_id == eid], batch, now)
+        # Suppressions are pure associations (no deleted_at) — hard-delete
+        # them here so restoring the project doesn't bring stale mutes back.
+        # FK CASCADE would handle a full DELETE on the project row, but the
+        # soft-delete path keeps the project row alive; this guarantees the
+        # rows are gone whether or not the project ever gets purged.
+        from sqlalchemy import delete as _sql_delete
+        from fabledassistant.models.rulebook import (
+            project_rule_suppressions, project_topic_suppressions,
+        )
+        await session.execute(
+            _sql_delete(project_rule_suppressions)
+            .where(project_rule_suppressions.c.project_id == eid)
+        )
+        await session.execute(
+            _sql_delete(project_topic_suppressions)
+            .where(project_topic_suppressions.c.project_id == eid)
+        )
         await _set(session, Project, [Project.user_id == user_id, Project.id == eid], batch, now)
     elif etype == "milestone":
         await _set(session, Note, [Note.user_id == user_id, Note.milestone_id == eid], batch, now)