Update fly.toml, .woodpecker.yml, and Dockerfile for deployment improvements

- Increased health check grace period in `fly.toml` to 30s.
- Added `dist` directory to cache mounts in `.woodpecker.yml`.
- Fixed file copy path in `Dockerfile` for accurate builds.

.woodpecker.yml

@@ -23,4 +23,5 @@ branches:
 cache:
   mount:
     - node_modules
-    - .npm
+    - .npm
+    - dist