DC-059: Joi validation middleware + schemas for destructive routes

[grade=B]

- New src/utilities/validate.js: validateBody(schema) middleware + 9 schemas
  (backupConfigUpdate, backupScheduleCreate, backupRestore, backupRestoreFile,
   appDeploy, appRestore, appRevert, assetUpload, logoUpload)
- Uses Joi's authoritative CIDR validator (rejects malformed IPv6 like ::::/64
  that the previous hex/colon regex would have accepted)
- appDeploy.config uses .unknown(true) for forward-compat with template-specific
  fields (sslType, dnsType, plexClaimToken, etc.) — preserves fields the live
  frontend posts, prevents a behavioural regression
- appRestore uses Joi.any().custom() so the empty-body semantics hold under
  middleware stripUnknown (default) — body with extra keys now rejected
- Wired into 8 destructive routes: backups schedule/restore/config, apps
  deploy/restore/revert, assets upload/logo
- Duplicate legacy POST /backups/schedule handler (line 519) marked LEGACY
  with TODO removal note (Express only matches first registration; this
  handler is unreachable under normal routing)
- Removed redundant manual appId check in /backups/schedule (Joi schema
  enforces it)
- Removed unused 'mime' destructure in /assets/favicon (decodeImageData
  validates MIME internally)
- 41 unit tests covering every exported schema + middleware integration
- 1539/1539 Jest tests pass, zero new ESLint warnings

dashcaddy-api/package-lock.json

@@ -15,6 +15,7 @@
         "express": "^4.22.1",
         "express-rate-limit": "^7.5.1",
         "helmet": "^8.1.0",
+        "joi": "^18.2.3",
         "js-yaml": "^4.1.1",
         "jsonwebtoken": "^9.0.2",
         "lru-cache": "^10.4.3",
@@ -679,6 +680,54 @@
         "node": ">=6"
       }
     },
+    "node_modules/@hapi/address": {
+      "version": "5.1.1",
+      "resolved": "https://registry.npmjs.org/@hapi/address/-/address-5.1.1.tgz",
+      "integrity": "sha512-A+po2d/dVoY7cYajycYI43ZbYMXukuopIsqCjh5QzsBCipDtdofHntljDlpccMjIfTy6UOkg+5KPriwYch2bXA==",
+      "license": "BSD-3-Clause",
+      "dependencies": {
+        "@hapi/hoek": "^11.0.2"
+      },
+      "engines": {
+        "node": ">=14.0.0"
+      }
+    },
+    "node_modules/@hapi/formula": {
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/@hapi/formula/-/formula-3.0.2.tgz",
+      "integrity": "sha512-hY5YPNXzw1He7s0iqkRQi+uMGh383CGdyyIGYtB+W5N3KHPXoqychklvHhKCC9M3Xtv0OCs/IHw+r4dcHtBYWw==",
+      "license": "BSD-3-Clause"
+    },
+    "node_modules/@hapi/hoek": {
+      "version": "11.0.7",
+      "resolved": "https://registry.npmjs.org/@hapi/hoek/-/hoek-11.0.7.tgz",
+      "integrity": "sha512-HV5undWkKzcB4RZUusqOpcgxOaq6VOAH7zhhIr2g3G8NF/MlFO75SjOr2NfuSx0Mh40+1FqCkagKLJRykUWoFQ==",
+      "license": "BSD-3-Clause"
+    },
+    "node_modules/@hapi/pinpoint": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/@hapi/pinpoint/-/pinpoint-2.0.1.tgz",
+      "integrity": "sha512-EKQmr16tM8s16vTT3cA5L0kZZcTMU5DUOZTuvpnY738m+jyP3JIUj+Mm1xc1rsLkGBQ/gVnfKYPwOmPg1tUR4Q==",
+      "license": "BSD-3-Clause"
+    },
+    "node_modules/@hapi/tlds": {
+      "version": "1.1.7",
+      "resolved": "https://registry.npmjs.org/@hapi/tlds/-/tlds-1.1.7.tgz",
+      "integrity": "sha512-MgNjRwy9Ti92yVAixLmDc8dd1bJIKwO9qlWCfFQRwRmUEDPQHYn4G6hwPFvFGUTzAa0FsS+inMjLin7GnyBRhA==",
+      "license": "BSD-3-Clause",
+      "engines": {
+        "node": ">=14.0.0"
+      }
+    },
+    "node_modules/@hapi/topo": {
+      "version": "6.0.2",
+      "resolved": "https://registry.npmjs.org/@hapi/topo/-/topo-6.0.2.tgz",
+      "integrity": "sha512-KR3rD5inZbGMrHmgPxsJ9dbi6zEK+C3ZwUwTa+eMwWLz7oijWUTWD2pMSNNYJAU6Qq+65NkxXjqHr/7LM2Xkqg==",
+      "license": "BSD-3-Clause",
+      "dependencies": {
+        "@hapi/hoek": "^11.0.2"
+      }
+    },
     "node_modules/@humanwhocodes/config-array": {
       "version": "0.13.0",
       "resolved": "https://registry.npmjs.org/@humanwhocodes/config-array/-/config-array-0.13.0.tgz",
@@ -1688,6 +1737,12 @@
         "@sinonjs/commons": "^3.0.0"
       }
     },
+    "node_modules/@standard-schema/spec": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/@standard-schema/spec/-/spec-1.1.0.tgz",
+      "integrity": "sha512-l2aFy5jALhniG5HgqrD6jXLi/rUWrKvqN/qJx6yoJsgKhblVd+iqqU4RCXavm/jPityDo5TCvKMnpjKnOriy0w==",
+      "license": "MIT"
+    },
     "node_modules/@types/babel__core": {
       "version": "7.20.5",
       "resolved": "https://registry.npmjs.org/@types/babel__core/-/babel__core-7.20.5.tgz",
@@ -4979,6 +5034,24 @@
         "url": "https://github.com/chalk/supports-color?sponsor=1"
       }
     },
+    "node_modules/joi": {
+      "version": "18.2.3",
+      "resolved": "https://registry.npmjs.org/joi/-/joi-18.2.3.tgz",
+      "integrity": "sha512-N5A3KTWQpPWT4ExxxPlUx7WmykGXRzhNidWhV41d6Abu9YfI2NyWCJuxdPnslJCPWtbRpSVOWSnSS6GakLM/Rg==",
+      "license": "BSD-3-Clause",
+      "dependencies": {
+        "@hapi/address": "^5.1.1",
+        "@hapi/formula": "^3.0.2",
+        "@hapi/hoek": "^11.0.7",
+        "@hapi/pinpoint": "^2.0.1",
+        "@hapi/tlds": "^1.1.1",
+        "@hapi/topo": "^6.0.2",
+        "@standard-schema/spec": "^1.1.0"
+      },
+      "engines": {
+        "node": ">= 20"
+      }
+    },
     "node_modules/js-tokens": {
       "version": "4.0.0",
       "resolved": "https://registry.npmjs.org/js-tokens/-/js-tokens-4.0.0.tgz",