feat: sync with upstream — v1.2.0, in-app updates, Projects, modules

Brings the public tree back in line with the development repo after several
weeks of drift caused by a stale publish include list.

New:
- In-app update path: GET /update/check compares the checkout against
  origin/main and POST /update/apply runs `ncp upgrade` detached (pull,
  rebuild, restart). The sidebar shows the version, checks on click, and
  offers an "update available" pill.
- Projects: a project workspace groups chats and RAG documents, with
  per-project instructions and document retrieval scoped to the active
  project. Replaces the standalone Documents page.
- modules/: auto-discovered feature plugins (mail, network) with their
  frontend counterparts and tests.
- Memory curation runs in-process (synapse/memory/curator.py) on the chat
  model when a conversation goes idle. The separate memory service on :8001
  is gone, along with the launcher lines that started it.

Also: the KDE theme, panel and Promethean terminal assets, the full test
suite, and VERSION 1.2.0.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

assets/themes/restore-snapshot/plank-dconf.ini

@@ -0,0 +1,19 @@
+[docks/dock1]
+alignment='center'
+auto-pinning=true
+current-workspace-only=false
+dock-items=['microsoft-edge.dockitem', 'promethean-terminal.dockitem', 'nexus-core.dockitem', 'code.dockitem', 'thunar.dockitem']
+hide-delay=0
+hide-mode='intelligent'
+icon-size=48
+items-alignment='center'
+lock-items=false
+offset=0
+pinned-only=false
+pressure-reveal=false
+show-dock-item=false
+theme='NexusOS'
+tooltips-enabled=true
+unhide-delay=0
+zoom-enabled=false
+zoom-percent=150