0.2.39: bitcoin-denominated view, first-login flow, unfunded + tax center

- BTC prices: btc_prices table, CSV upload on Import page (auto-detected
  date/close columns, upsert by date), entities.close_date as the BTC entry
  mark; statements carry btc_price_cents (as-of) + btc_close_price_cents.
  LP capital blocks show paid-in vs current value in bitcoin terms.
- First login: accounts on the shared default password are flagged
  (must_change_password) and blocked behind a full-screen password change;
  external accounts then get a one-time welcome tour with a 2FA offer
  (users.onboarded_at).
- LP portal: Unfunded (callable commitment) metric; Tax documents center
  aggregating K-1/tax docs across funds, grouped by year.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

deploy/package.json

@@ -1,6 +1,6 @@
 {
   "name": "ten31portal-startos",
-  "version": "0.2.38",
+  "version": "0.2.39",
   "private": true,
   "scripts": {
     "build": "npm run check && rm -rf ./javascript && ncc build startos/index.ts -o ./javascript",