Release 0.2.21; track the StartOS version files

Cut version 0.2.21 (current = v_0_2_21) with the adjudicated DO-item fixes.
Also commits the previously-untracked v_0_2_* version files that
versions/index.ts imports (ROADMAP item D2), so a fresh checkout builds
without dangling imports. The missing v_0_2_2 is intentional (versions are
an unordered set).

Built and verified: ten31portal_x86_64.s9pk packs cleanly at 0.2.21:0,
arch x86_64, SDK 0.4.0.

deploy/startos/install/versions/v_0_2_21.ts

@@ -0,0 +1,13 @@
+import { VersionInfo } from '@start9labs/start-sdk'
+
+export const v_0_2_21 = VersionInfo.of({
+  version: '0.2.21:0',
+  releaseNotes: {
+    en_US:
+      'Importing with replace-existing-holdings now asks for confirmation before clearing a fund, and shows step-by-step progress. You can expand an audit log entry to see its full detail. Entities with no investments show a clear empty state. A brief server hiccup shows a retry prompt instead of logging you out. Backend adds document upload size limits, database indexes, and an automated test suite.',
+  },
+  migrations: {
+    up: async ({ effects }) => {},
+    down: async ({ effects }) => {},
+  },
+})