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.

fly.toml

@@ -26,7 +26,7 @@ kill_timeout = 5
   [[http_service.checks]]
     interval = "30s"
     timeout = "5s"
-    grace_period = "10s"
+    grace_period = "30s"
     method = "GET"
     path = "/"
     protocol = "http"