feat: add QMD v2.1.0 as Nix package, bake into openclaw image

- packages/qmd: buildNpmPackage with Node.js 22 (not Bun) to avoid
  native module ABI issues with better-sqlite3 and sqlite-vec
- Vendored package-lock.json (QMD ships bun.lock, not npm lockfile)
- packages/openclaw-image: adds qmd + tsx to image contents
- packages/default.nix: rec attrset so openclaw-image can inherit qmd
- flake.nix: expose custom-qmd package output for CI caching

packages/openclaw-image/default.nix

@@ -1,6 +1,7 @@
 {
   pkgs,
   lib,
+  qmd,
 }:
 
 let
@@ -38,14 +39,14 @@ let
         ];
       }
       ''
-              mkdir -p $out/app
+        mkdir -p $out/app
 
-              # Extract all layers from the Docker image tarball
-              mkdir workdir
-              tar xf ${openclawBase} -C workdir
+        # Extract all layers from the Docker image tarball
+        mkdir workdir
+        tar xf ${openclawBase} -C workdir
 
-              # Python: parse manifest, generate shell script to extract /app from layers
-              python3 << 'PYEOF'
+        # Python: parse manifest, generate shell script to extract /app from layers
+        python3 << 'PYEOF'
         import json
 
         with open("workdir/manifest.json") as f:
@@ -71,14 +72,14 @@ let
         """)
         PYEOF
 
-              OUT_DIR="$out" sh extract.sh
+        OUT_DIR="$out" sh extract.sh
 
-              if [ ! -f "$out/app/openclaw.mjs" ]; then
-                echo "ERROR: /app/openclaw.mjs not found after extraction"
-                ls -la $out/app/ 2>/dev/null || true
-                exit 1
-              fi
-              echo "Successfully extracted openclaw app"
+        if [ ! -f "$out/app/openclaw.mjs" ]; then
+          echo "ERROR: /app/openclaw.mjs not found after extraction"
+          ls -la $out/app/ 2>/dev/null || true
+          exit 1
+        fi
+        echo "Successfully extracted openclaw app"
       '';
 
   # Python environment with pymupdf
@@ -87,20 +88,20 @@ let
   # Custom NSS files that include the "node" user (UID 1000, GID 1000).
   # fakeNss only creates root/nobody, so we create our own with all three.
   openclawNss = pkgs.runCommand "openclaw-nss" { } ''
-        mkdir -p $out/etc
-        cat > $out/etc/passwd << 'EOF'
+    mkdir -p $out/etc
+    cat > $out/etc/passwd << 'EOF'
     root:x:0:0:root user:/var/empty:/bin/sh
     nobody:x:65534:65534:nobody:/var/empty:/bin/sh
     node:x:1000:1000::/home/node:/bin/bash
     EOF
 
-        cat > $out/etc/group << 'EOF'
+    cat > $out/etc/group << 'EOF'
     root:x:0:
     nobody:x:65534:
     node:x:1000:
     EOF
 
-        cat > $out/etc/shadow << 'EOF'
+    cat > $out/etc/shadow << 'EOF'
     root:!x:::::::
     nobody:!x:::::::
     node:!x:::::::
@@ -172,14 +173,20 @@ pkgs.dockerTools.buildLayeredImage {
     pkgs.git
     pkgs.emacs
 
-    # Node.js 22+ (for openclaw runtime, QMD when packaged, matrix-bot-sdk)
+    # Node.js 22+ (for openclaw runtime, QMD, matrix-bot-sdk)
     pkgs.nodejs_22
 
+    # TypeScript runtime (for running TypeScript files directly, e.g. via nix run)
+    pkgs.tsx
+
     # Python with pymupdf (PDF-to-image for Claude vision)
     pythonEnv
 
     # Gitea CLI (PR workflow)
     pkgs.tea
+
+    # QMD — on-device hybrid search for markdown (built with Node.js 22, not Bun)
+    qmd
   ];
   # NOTE: openclawApp is NOT in contents. It would create /app as a symlink
   # to /nix/store/..., which breaks OpenClaw's symlink escape security check