fix: resolve runtime crashes in tool-ui components and backend import errors

Backend:
- Remove dead imports (display_image, link_preview, knowledge_base) from tools registry and __init__
- Delete orphaned elif chain (lines 784-1046) in knowledge_base.py left after asyncio.gather refactor
- Add missing NotionAPIError class to notion_history.py

Frontend:
- Add display-image.tsx, link-preview.tsx, scrape-webpage.tsx tool UI components
- Fix GeneratePodcastToolUI: add null guard for no-props render + optional chaining on status/args
- Fix SaveMemoryToolUI/RecallMemoryToolUI: add null guard when rendered without props in provider
- Update launch.json to use pnpm on port 3999

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

.claude/launch.json

@@ -3,10 +3,11 @@
   "configurations": [
     {
       "name": "SurfSense Frontend",
-      "runtimeExecutable": "bun",
+      "runtimeExecutable": "pnpm",
       "runtimeArgs": ["dev"],
       "cwd": "surfsense_web",
-      "port": 3000
+      "port": 3999,
+      "autoPort": false
     },
     {
       "name": "SurfSense Backend",