Fix Electron not opening: run npm install on core + check DISPLAY

- core.sh: run npm install after cloning (downloads Electron binary
  into app/node_modules — required for the UI to launch)
- start.sh template: check if app/node_modules exists and run
  npm install on first start if missing
- start.sh template: warn if DISPLAY/WAYLAND_DISPLAY not set

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

lib/container.sh

@@ -100,6 +100,18 @@ if ! "\$RUNTIME" container inspect "\$CONTAINER_NAME" --format '{{.State.Running
     echo "Error: container failed to start." >&2; exit 1
 fi
 
+# ── Ensure core deps are installed (Electron binary lives here) ─────────
+if [[ ! -d "\$CS_CORE/app/node_modules" ]]; then
+    echo "→ Installing context-studio-core dependencies (first run)..."
+    (cd "\$CS_CORE" && npm install) || { echo "npm install failed." >&2; exit 1; }
+fi
+
+# ── Check display for Electron UI ───────────────────────────────────────
+if [[ -z "\${DISPLAY:-}" && -z "\${WAYLAND_DISPLAY:-}" ]]; then
+    echo "⚠  No display detected (DISPLAY / WAYLAND_DISPLAY not set)."
+    echo "   Electron UI may not open. Set DISPLAY=:0 or run from a desktop terminal."
+fi
+
 # ── Put claude wrapper first on PATH ────────────────────────────────────
 export PATH="\$PROJECT_DIR/bin:\$PATH"
 

lib/core.sh

@@ -24,5 +24,8 @@ setup_core() {
     spin "Cloning context-studio-core..." \
         git clone "$CS_CORE_REPO" "$CS_CORE_DIR" \
         || die "Failed to clone context-studio-core. Check your SSH key and network."
+    spin "Installing core dependencies (npm install)..." \
+        bash -c "cd '$CS_CORE_DIR' && npm install" \
+        || die "npm install failed for context-studio-core."
     success "Core installed at $CS_CORE_DIR"
 }