Merge origin/main into feat/plugin-catalog

Python plugin CLI/loader/web/tui files taken from main wholesale; the
catalog layer is re-ported onto main's decomposed shapes in the
following commits. plugin_index.py removed (catalog is the sole
discovery system).

.gitignore

@@ -98,15 +98,19 @@ apps/desktop/src/**/*.d.ts
 !apps/desktop/src/global.d.ts
 !apps/desktop/src/vite-env.d.ts
 
-# Repo-root build/debug artifacts that must never be committed
+# Build/debug artifacts that must never be committed
 /log.txt
 /sqlite_leak_fix.png
 /*.png.bak
-/default.tar.gz
+*.tar.gz
+*.tgz
 apps/shared/src/**/*.js
 apps/shared/src/**/*.js.map
 apps/shared/src/**/*.d.ts
 apps/desktop/release/
+# stage-and-swap Desktop rebuild output (#86443); removed after the swap, but
+# a killed build must not leave the checkout dirty
+apps/desktop/.staging-*/
 *.tsbuildinfo
 
 # Web UI assets — synced from @nous-research/ui at build time via
@@ -215,3 +219,7 @@ native/fts5_cjk/*.so
 # interrupted; consumed by launch-time recovery. Never commit it (was tracked
 # by accident via 3a69e34702, removed in the #72002 salvage).
 .lazy-refresh-incomplete
+.skills_prompt_snapshot.json
+
+# Disposable profile created by scripts/probe_active_session_exclusivity.py
+.probe-home/