revert(build): remove app build pipeline revamp (Nixpacks/MinIO/Trivy/registry GC)

Reverts commits 3eff38f and c379a23 and restores the previous Kaniko-only
build pipeline (runtime detection + per-runtime Dockerfile generation,
disk-based source upload).

Removed: Nixpacks Dockerfile generation, MinIO source storage (common/storage),
Bull build queue + Redis build state (common/redis, deployment.processor),
Trivy image scan (scan.service, deployment.vulnerabilitySummary), and daily
registry garbage collection (registry-gc). Nothing outside the build/deploy
path depended on these. Backend tsc + 105/106 tests green (the pre-existing
helm.service chartPath failure is unrelated); frontend tsc green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/package.json

@@ -38,7 +38,6 @@
     "handlebars": "^4.7.8",
     "helmet": "^8.2.0",
     "js-yaml": "^4.2.0",
-    "minio": "^8.0.7",
     "multer": "^2.1.1",
     "passport": "^0.7.0",
     "passport-jwt": "^4.0.1",
@@ -70,19 +69,13 @@
     "typescript": "^6.0.0"
   },
   "jest": {
-    "moduleFileExtensions": [
-      "js",
-      "json",
-      "ts"
-    ],
+    "moduleFileExtensions": ["js", "json", "ts"],
     "rootDir": "src",
     "testRegex": ".*\\.spec\\.ts$",
     "transform": {
       "^.+\\.(t|j)s$": "ts-jest"
     },
-    "collectCoverageFrom": [
-      "**/*.(t|j)s"
-    ],
+    "collectCoverageFrom": ["**/*.(t|j)s"],
     "coverageDirectory": "../coverage",
     "testEnvironment": "node"
   }