feat: pre-generate Directus image previews

Bundle extension (upload hook + API endpoint + admin module) that warms
Directus image transform cache in-process with an explicit acceptFormat,
so the generated file matches the browser's cache key byte-for-byte.

- resumable, window-aware backfill with progress + cancel
- system + custom presets, effective-format reporting, shadow warnings
- storage breakdown (previews vs originals), human-readable API fields
- diagnostics: resolve-plan prediction, per-file generate, ops ring buffer
- isolated dev/staging compose stack + deploy/rollback scripts

Verified on Directus 11.17.4: 40/40 tests, hash-match gate passed,
idempotent backfill, custom fixed-format presets, error surfacing.

package.json

@@ -0,0 +1,63 @@
+{
+  "name": "directus-extension-generate-image-previews",
+  "description": "Pre-generate Directus image transforms: on upload, on demand, and via a scheduled resumable backfill, with an admin UI (progress, disk usage, maintenance window)",
+  "author": {
+    "name": "Rawman Grey",
+    "email": "rawman@locus.im",
+    "url": "https://locus.im"
+  },
+  "icon": "extension",
+  "version": "0.1.0",
+  "keywords": [
+    "directus",
+    "directus-extension",
+    "directus-extension-bundle"
+  ],
+  "type": "module",
+  "files": [
+    "dist"
+  ],
+  "directus:extension": {
+    "type": "bundle",
+    "path": {
+      "app": "dist/app.js",
+      "api": "dist/api.js"
+    },
+    "entries": [
+      {
+        "type": "module",
+        "name": "image-previews",
+        "source": "src/module/index.ts"
+      },
+      {
+        "type": "hook",
+        "name": "image-previews-hook",
+        "source": "src/hook/index.ts"
+      },
+      {
+        "type": "endpoint",
+        "name": "image-previews-endpoint",
+        "source": "src/endpoint/index.ts"
+      }
+    ],
+    "host": "^10.10.0 || ^11.0.0"
+  },
+  "scripts": {
+    "build": "directus-extension build",
+    "dev": "directus-extension build -w --no-minify",
+    "link": "directus-extension link",
+    "typecheck": "tsc --noEmit",
+    "test": "node --import tsx --test src/lib/*.test.ts",
+    "publish": "scp -r ./dist ./package.json land-nest:/home/oak/apps/directus/extensions/directus-extension-generate-image-previews/"
+  },
+  "devDependencies": {
+    "@directus/extensions-sdk": "13.0.1",
+    "@types/node": "^22.13.5",
+    "tsx": "^4.19.2",
+    "typescript": "^5.7.3",
+    "vue": "^3.5.13"
+  },
+  "dependencies": {
+    "object-hash": "^3.0.0"
+  }
+}