chore: cut agent token burn with scoped bootstrap and handoffs

Slim always-on agent docs, default to toju-app plus targeted electron, and add HANDOFF.md plus a Cursor rule so long chats reset cleanly without agents opening new chats.

Co-authored-by: Cursor <cursoragent@cursor.com>

.cursorignore

@@ -0,0 +1,27 @@
+# Reduce indexing / accidental bulk reads. Scope policy lives in AGENTS.md.
+# Do NOT list electron/, server/, e2e/, website/, or docs-site/ here —
+# those stay reachable when the user explicitly expands scope.
+
+node_modules/
+**/node_modules/
+dist/
+dist-electron/
+dist-server/
+.angular/
+coverage/
+test-results/
+e2e/playwright-report/
+docs-site/.docusaurus/
+docs-site/build/
+*.sqlite
+package-lock.json
+
+# Media / binary bulk
+images/
+**/*.png
+**/*.jpg
+**/*.jpeg
+**/*.webp
+**/*.gif
+**/*.mp4
+**/*.wasm