feat(rag): RAG scoping and context isolation controls

- Migration 0030: add conversations.rag_project_id (NULL=orphan-only,
  -1=all notes, positive=project), projects.auto_summary and
  projects.summary_updated_at
- Three-value scope semantics thread from build_context() → semantic
  search and keyword fallback via orphan_only + effective_project_id
- Project summarization background job (generate_project_summary,
  backfill_project_summaries) called via Ollama; triggered on project
  update and note saves (debounced 1h); runs at startup
- New LLM tools: search_projects (SequenceMatcher scoring on
  title+description+auto_summary) and set_rag_scope (persists to DB,
  workspace-guarded, emits new_rag_scope in SSE done event)
- execute_tool() accepts conv_id + workspace_project_id; generation_task
  passes both and captures scope changes for SSE done enrichment
- Frontend: Conversation type gets rag_project_id; chat store adds
  ragProjectId computed + updateRagScope(); SSE done handler syncs scope
- ChatView: replace sidebar ProjectSelector with a scope chip pill above
  the input bar, animated dropdown, pulse on model-driven scope change

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/fabledassistant/services/notes.py

@@ -22,6 +22,29 @@ def _normalize_tags(tags: list[str]) -> list[str]:
     return out
 
 
+async def _maybe_trigger_project_summary(user_id: int, project_id: int) -> None:
+    """Fire generate_project_summary() if the project summary is missing or >1h old."""
+    import asyncio
+    from datetime import timedelta
+    from fabledassistant.models.project import Project
+    from fabledassistant.services.projects import generate_project_summary
+    try:
+        async with async_session() as session:
+            project = (await session.execute(
+                select(Project).where(Project.id == project_id)
+            )).scalars().first()
+        if project is None:
+            return
+        stale = (
+            project.summary_updated_at is None
+            or (datetime.now(timezone.utc) - project.summary_updated_at) > timedelta(hours=1)
+        )
+        if stale:
+            asyncio.create_task(generate_project_summary(user_id, project_id))
+    except Exception:
+        logger.debug("_maybe_trigger_project_summary failed for project %d", project_id, exc_info=True)
+
+
 async def create_note(
     user_id: int,
     title: str = "",
@@ -61,7 +84,11 @@ async def create_note(
         session.add(note)
         await session.commit()
         await session.refresh(note)
-        return note
+
+    if project_id is not None:
+        await _maybe_trigger_project_summary(user_id, project_id)
+
+    return note
 
 
 async def get_note(user_id: int, note_id: int) -> Note | None:
@@ -222,6 +249,9 @@ async def update_note(user_id: int, note_id: int, **fields: object) -> Note | No
         from fabledassistant.services.note_versions import create_version
         await create_version(user_id, note_id, old_body, old_title, old_tags)
 
+    if note.project_id is not None:
+        await _maybe_trigger_project_summary(user_id, note.project_id)
+
     return note
 
 
@@ -303,6 +333,7 @@ async def search_notes_for_context(
     exclude_ids: set[int] | None = None,
     limit: int = 3,
     project_id: int | None = None,
+    orphan_only: bool = False,
 ) -> list[Note]:
     """Search notes by keywords with OR logic. Optimized for context building — no count query."""
     async with async_session() as session:
@@ -313,7 +344,9 @@ async def search_notes_for_context(
             keyword_filters.append(or_(Note.title.ilike(pattern), Note.body.ilike(pattern)))
 
         query = select(Note).where(Note.user_id == user_id, or_(*keyword_filters))
-        if project_id is not None:
+        if orphan_only:
+            query = query.where(Note.project_id.is_(None))
+        elif project_id is not None:
             query = query.where(Note.project_id == project_id)
         if exclude_ids:
             query = query.where(Note.id.notin_(exclude_ids))