Release 0.2.22: capital chart, Investor View, GP stakes, doc folders

Snapshot commit bringing the uncommitted phase-2 work into version control
together with four new features and the 0.2.22 version bump.

New features:
- Investor capital-over-time chart (value, paid-in, distributions per
  quarter), rendered from existing capital-account history.
- Admin Investor View: read-only reconstruction of an investor's portal
  (GET /api/users/{id}/investor-view), reusing the investor portal UI.
- Document upload scoped to the selected fund's own investors, with an
  explicit upload-target confirmation to prevent mis-attaching.
- GP/mgmt entities gain an Assets tab listing their stakes in the funds
  they manage (new entity_stakes table + /api/entities/{id}/stakes).
- Edit-entity form (change type/status/etc.), so GP entities can be
  categorized correctly.

Verified: 11/11 backend tests pass; alembic upgrades to head b8c9d0e1f2a3;
frontend tsc + vite build clean; s9pk packs at 0.2.22:0 (x86_64).
Also: ignore .DS_Store and *.s9pk artifacts.

frontend/src/version.ts

@@ -0,0 +1,4 @@
+// Bumped each release so the running build is visible in the UI.
+// If the number shown in the app doesn't match the installed s9pk version,
+// the new frontend isn't actually being served.
+export const APP_VERSION = "0.2.20";