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.

src/lib/types.ts

@@ -0,0 +1,50 @@
+export interface Preset {
+	key: string;
+	format?: string;
+	quality?: number | string;
+	width?: number | string;
+	height?: number | string;
+	fit?: string;
+	withoutEnlargement?: boolean;
+	focal_point_x?: number | string | null;
+	focal_point_y?: number | string | null;
+	transforms?: unknown[];
+	[key: string]: unknown;
+}
+
+export interface WarmResultItem {
+	key: string;
+	format: string | null;
+	ok: boolean;
+	ms: number;
+	error?: string;
+}
+
+export interface WarmSummary {
+	requested: number;
+	ok: number;
+	failed: number;
+	results: WarmResultItem[];
+}
+
+export interface CompletedRecord {
+	file_id: string;
+	preset_key: string;
+	format: string | null;
+	ts: number;
+}
+
+export interface RunState {
+	running: boolean;
+	startedAt: number | null;
+	finishedAt: number | null;
+	total: number;
+	done: number;
+	generated: number;
+	hits: number;
+	failed: number;
+	rate: number;
+	eta: number | null;
+	cancelled: boolean;
+	error?: string;
+}