feat: git-like project versioning (v1)

Linear per-project history per notes/project-versioning.md: named
checkpoints (thumbnail via renderer.captureFrame) plus auto-checkpoints
on save (60s throttle, ring of 20, named never rotate). Restore writes a
safety checkpoint first, then swaps the document outside undo/redo.
Media assets referenced by any version are pinned against deletion.
Migration v31-v32 stamps the schema; the version store lives in its own
IDB database with an in-memory fallback for tests. Versions popover in
the editor header for jump/rename/delete. 12 new tests.

1 files changed, 31 insertions, 0 deletions

diff --git a/apps/web/src/services/storage/migrations/transformers/v31-to-v32.ts b/apps/web/src/services/storage/migrations/transformers/v31-to-v32.ts
new file mode 100644
index 00000000..bedb4784
--- /dev/null
+++ b/apps/web/src/services/storage/migrations/transformers/v31-to-v32.ts
@@ -0,0 +1,31 @@
+import type { MigrationResult, ProjectRecord } from "./types";
+import { getProjectId } from "./utils";
+
+/**
+ * v31 → v32 introduces the `projectVersions` store (named checkpoints +
+ * auto-checkpoints; see notes/project-versioning.md). The store lives in its
+ * own IndexedDB database created lazily by the versions adapter, so project
+ * records need no shape change — this migration only stamps the new version.
+ */
+export function transformProjectV31ToV32({
+	project,
+}: {
+	project: ProjectRecord;
+}): MigrationResult<ProjectRecord> {
+	if (!getProjectId({ project })) {
+		return { project, skipped: true, reason: "no project id" };
+	}
+
+	const version = project.version;
+	if (typeof version !== "number") {
+		return { project, skipped: true, reason: "invalid version" };
+	}
+	if (version >= 32) {
+		return { project, skipped: true, reason: "already v32" };
+	}
+	if (version !== 31) {
+		return { project, skipped: true, reason: "not v31" };
+	}
+
+	return { project: { ...project, version: 32 }, skipped: false };
+}