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/projects.py

@@ -70,6 +70,7 @@ async def list_projects(user_id: int, status: str | None = None) -> list[Project
 
 
 async def update_project(user_id: int, project_id: int, **fields: object) -> Project | None:
+    import asyncio
     async with async_session() as session:
         result = await session.execute(
             select(Project).where(Project.id == project_id, Project.user_id == user_id)
@@ -83,7 +84,72 @@ async def update_project(user_id: int, project_id: int, **fields: object) -> Pro
         project.updated_at = datetime.now(timezone.utc)
         await session.commit()
         await session.refresh(project)
-        return project
+    asyncio.create_task(generate_project_summary(user_id, project_id))
+    return project
+
+
+async def generate_project_summary(user_id: int, project_id: int) -> None:
+    """Generate an LLM summary for a project and persist it. Fire-and-forget safe."""
+    try:
+        async with async_session() as session:
+            project = (await session.execute(
+                select(Project).where(Project.id == project_id, Project.user_id == user_id)
+            )).scalars().first()
+            if project is None:
+                return
+
+            note_rows = (await session.execute(
+                select(Note.title, Note.body)
+                .where(Note.project_id == project_id, Note.user_id == user_id)
+                .order_by(Note.updated_at.desc())
+                .limit(10)
+            )).all()
+
+        title = project.title or ""
+        description = project.description or ""
+        goal = project.goal or ""
+        note_snippets = "\n".join(
+            f"- {r.title}: {(r.body or '')[:200]}" for r in note_rows
+        )
+
+        prompt = (
+            f"Summarize this project in 3-4 sentences covering its purpose, themes, and content.\n"
+            f"Title: {title}\nDescription: {description}\nGoal: {goal}\n"
+            f"Recent notes:\n{note_snippets}"
+        )
+
+        from fabledassistant.services.llm import generate_completion
+        from fabledassistant.config import Config
+        messages = [{"role": "user", "content": prompt}]
+        summary = await generate_completion(messages, model=Config.OLLAMA_MODEL, max_tokens=400)
+        if not summary:
+            return
+
+        async with async_session() as session:
+            project = (await session.execute(
+                select(Project).where(Project.id == project_id)
+            )).scalars().first()
+            if project:
+                project.auto_summary = summary.strip()
+                project.summary_updated_at = datetime.now(timezone.utc)
+                await session.commit()
+        logger.debug("Generated summary for project %d", project_id)
+    except Exception:
+        logger.debug("Failed to generate summary for project %d", project_id, exc_info=True)
+
+
+async def backfill_project_summaries() -> None:
+    """Generate summaries for all projects missing auto_summary. Fire-and-forget."""
+    import asyncio
+    try:
+        async with async_session() as session:
+            rows = (await session.execute(
+                select(Project.id, Project.user_id).where(Project.auto_summary.is_(None))
+            )).all()
+        for row in rows:
+            asyncio.create_task(generate_project_summary(row.user_id, row.id))
+    except Exception:
+        logger.debug("backfill_project_summaries failed", exc_info=True)
 
 
 async def delete_project(user_id: int, project_id: int) -> bool: