feat(ui): avatar crop modal, health endpoint, leaner Dockerfile

- Add AvatarCropModal.svelte using cropperjs v1: 1:1 crop, 400×400 output,
  JPEG/WebP output, dark glassmorphic UI
- Rewrite profile page avatar upload to use presigned PUT flow (POST→PUT→PATCH)
  instead of sending raw FormData directly; crop modal opens on file select
- Add GET /health → {status:ok} for Docker healthcheck
- Simplify Dockerfile: drop runtime npm ci (adapter-node bundles all deps)
- Fix docker-compose UI healthcheck: /health route, 127.0.0.1 to avoid
  IPv6 localhost resolution failure in alpine busybox wget

ui/package-lock.json

@@ -10,6 +10,7 @@
 			"dependencies": {
 				"@aws-sdk/client-s3": "^3.1005.0",
 				"@aws-sdk/s3-request-presigner": "^3.1005.0",
+				"cropperjs": "^1.6.2",
 				"marked": "^17.0.3",
 				"pocketbase": "^0.26.8"
 			},
@@ -3114,6 +3115,12 @@
 				"node": ">= 0.6"
 			}
 		},
+		"node_modules/cropperjs": {
+			"version": "1.6.2",
+			"resolved": "https://registry.npmjs.org/cropperjs/-/cropperjs-1.6.2.tgz",
+			"integrity": "sha512-nhymn9GdnV3CqiEHJVai54TULFAE3VshJTXSqSJKa8yXAKyBKDWdhHarnlIPrshJ0WMFTGuFvG02YjLXfPiuOA==",
+			"license": "MIT"
+		},
 		"node_modules/deepmerge": {
 			"version": "4.3.1",
 			"resolved": "https://registry.npmjs.org/deepmerge/-/deepmerge-4.3.1.tgz",