feat: initial tools service with document scanner, image & PDF tools

Self-hosted document scanner and media processing tools.
- Rust Axum gateway + worker pool with NATS JetStream
- Next.js 16 frontend with shadcn/ui
- Scanner pipeline: edge detection, warp, binarization, OCR
- Image tools: compress, resize, convert
- PDF tools: merge, split, compress
- CI/CD with Docker multi-stage build

Co-Authored-By: Kilo <kilo@kilo.ai>

frontend/public/manifest.json

@@ -0,0 +1,13 @@
+{
+  "name": "Tools — Asep Haryana",
+  "short_name": "Tools",
+  "description": "Document Scanner, Image & PDF Tools",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#0a0a1a",
+  "theme_color": "#0a0a1a",
+  "icons": [
+    { "src": "/icons/icon-192.png", "sizes": "192x192", "type": "image/png" },
+    { "src": "/icons/icon-512.png", "sizes": "512x512", "type": "image/png" }
+  ]
+}