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/install-theme.sh

@@ -74,7 +74,12 @@ echo "NexusOS theme — restoring wiring from $REPO"
 
 echo "[1/4] Symlinks"
 link "$REPO/assets/themes/NexusOS"          "$HOME/.themes/NexusOS"
+# Icons go in BOTH places on purpose. ~/.icons is the GTK/XFCE legacy path and
+# is all this used to install; Qt/KF5 searches XDG data dirs only, so under
+# Plasma the theme was never found and every icon silently fell back to Breeze
+# (`kiconfinder5 nexusos-logo` returned nothing at all).
 link "$REPO/assets/themes/NexusOS-icons"    "$HOME/.icons/NexusOS"
+link "$REPO/assets/themes/NexusOS-icons"    "$HOME/.local/share/icons/NexusOS"
 link "$REPO/assets/themes/gtk3-user-overrides.css" "$HOME/.config/gtk-3.0/gtk.css"
 
 echo "[2/4] xfconf (xsettings + xfwm4)"
@@ -98,7 +103,10 @@ echo "[4/4] Icon caches"
 gtk-update-icon-cache -f -t "$HOME/.icons/NexusOS" 2>/dev/null \
     && say "ok    NexusOS icon cache rebuilt" \
     || say "WARN  NexusOS icon cache rebuild failed"
-INH="$(grep -i '^Inherits=' "$REPO/assets/themes/NexusOS-icons/index.theme" 2>/dev/null | cut -d= -f2)"
+# Inherits is a comma-separated list, so check the first (primary) parent
+# rather than the whole string — treating "breeze-dark,hicolor" as one theme
+# name found no such directory and warned about a fallback that is installed.
+INH="$(grep -i '^Inherits=' "$REPO/assets/themes/NexusOS-icons/index.theme" 2>/dev/null | cut -d= -f2 | cut -d, -f1)"
 if [[ -n "$INH" ]]; then
     INH_OK=0
     for dir in /usr/share/icons ~/.icons ~/.local/share/icons; do