Install scene: fix cmd-bar overlap, swap install command

The "CLICK TO COPY" hint was absolute-positioned at top:10/right:14 of
the cmd-box, landing on top of "~/facere — bash" in the bar header.
Move the hint into the bar as a flex sibling so the title and hint
share the row cleanly without overlap.

Replace the placeholder install command with the real installer pulled
from raw.githubusercontent.com, with FACERE_GH_TOKEN as a
"contact us for demo" placeholder.

Also fix deploy/build.sh: `npm init -y` rejects the leading-dot dir
name `.build`, and the preset must be resolved by absolute path since
babel runs from the repo root.

deploy/build.sh

@@ -15,13 +15,20 @@ BUILD_DIR=".build"
 mkdir -p "$BUILD_DIR"
 
 if [ ! -f "$BUILD_DIR/package.json" ]; then
-  ( cd "$BUILD_DIR" && npm init -y >/dev/null \
-      && npm install --silent --no-audit --no-fund \
-         @babel/core@7 @babel/cli@7 @babel/preset-react@7 )
+  # Write package.json directly — `npm init -y` rejects the leading-dot dir name.
+  cat > "$BUILD_DIR/package.json" <<'EOF'
+{ "name": "facere-build", "version": "1.0.0", "private": true }
+EOF
+fi
+if [ ! -d "$BUILD_DIR/node_modules/@babel/preset-react" ]; then
+  ( cd "$BUILD_DIR" && npm install --silent --no-audit --no-fund \
+       @babel/core@7 @babel/cli@7 @babel/preset-react@7 )
 fi
 
+# Resolve the preset by absolute path: babel CLI runs from the repo root and
+# wouldn't find it via the bare name (preset lives in .build/node_modules).
 "$BUILD_DIR/node_modules/.bin/babel" app.jsx \
-  --presets=@babel/preset-react \
+  --presets="$ROOT/$BUILD_DIR/node_modules/@babel/preset-react" \
   -o app.js
 
 echo "Built app.js ($(wc -c < app.js) bytes)"