Pluggable AI providers, relay credit system, picker UX overhaul

Captures roughly forty version bumps (v0.2.6 → v0.2.47) of work that
accumulated without commits.

- Pluggable provider system under server/providers/: gemini, anthropic,
  openai, openai-compatible, ollama, whisper-compatible, relay. Mix and
  match transcription + analysis per request via the picker UI.
- Relay backend integration. Hardcoded relay URL in server/relay-default.js
  (operator-controlled at build time, not user-configurable). New
  /api/relay/{status,policy} endpoints proxy to the relay; balance pings
  populate a cached credit display.
- Per-install identity in server/install-id.js for relay credit accounting.
  Sent to the relay as X-Recap-Install-Id; persists across upgrades, lost
  on a full uninstall + reinstall. Not surfaced in the UI.
- Admin login gate (server/admin-auth.js + setAdminPassword action). Scrypt
  password hash + HMAC-signed session cookie.
- Entitlement scheme rename: pro / max (each paired with subscriptions and
  relay_pro / relay_max), replacing the misleading "core" entitlement
  that conflicted with the user-facing "Core" tier name.
- Activation screen: dynamic credit count pulled from /api/relay/policy,
  "Skip — use free mode" button, accurate paid-feature list.
- Top toolbar: inline credit-balance pill (or "BYO configured" fallback),
  Upgrade + "I have a key" buttons.
- Picker UI: per-provider sections with Save/Test/Delete buttons, sections
  collapsible by chevron, default-collapsed unless currently selected,
  "Use comped credits (reset to relay)" link when the user has strayed,
  green hint under inputs whose values are server-configured.
- Activity log: chevron-collapsible groups per video, refresh-survival via
  localStorage + a 500-entry server-side buffer, explicit Clear button.
- YouTube captions fast-path with user toggle (skips audio download + AI
  transcription when captions are available — uncheck for speaker labels).
- Cancel button: AbortController plumbed through every provider SDK call;
  retryAPI short-circuits on AbortError; cancellation events surface in
  the activity log instead of silent retries.
- Long-video analysis: auto-coalesce transcript entries before building the
  analysis prompt so local-model context windows (32k-ish) don't overflow.
  Original entries preserved for transcript display via an index map; the
  analyzer sees a coarser view but click-to-seek timestamps stay precise.
- StartOS action grouping (Setup / AI Providers) so the actions list is
  navigable.
- Manifest description rewritten to reflect multi-provider support and
  free-tier relay credits.
- Smaller fixes: summarize-button enablement no longer requires a Gemini
  key when other providers are configured; analysis fallback chain handles
  context-length and 503 capacity errors; single-segment expansion for
  providers that don't return per-segment timestamps (Parakeet et al.);
  many other UX polish items.

server/relay-state.js

@@ -0,0 +1,52 @@
+// In-memory cache of the most recent relay-reported credit balance + tier.
+// Updated every time a relay provider call lands (success or 4xx error
+// that includes the standard envelope). Exposed via /api/relay/status
+// so the UI can render the "N credits remaining · Tier: X" banner
+// without re-hitting the relay just for status.
+//
+// Not persisted to disk — the relay is the source of truth. We just cache
+// the last response so the UI doesn't have to wait for the next request
+// to refresh the display. On a fresh boot the cache is empty until the
+// first /api/relay/status call, which can optionally probe the relay.
+
+let lastSnapshot = {
+  creditsRemaining: null,   // number | null
+  tier: null,               // "core" | "pro" | "max" | null
+  lastUpdated: null,        // ms-epoch | null
+  lastError: null,          // string | null
+};
+
+// Called by the relay provider on every response (including error
+// responses that the relay annotated with the standard envelope).
+// `envelope` is the parsed JSON shape: { credits_remaining, tier, ... }.
+export function updateRelayState(envelope) {
+  if (!envelope || typeof envelope !== "object") return;
+  if (typeof envelope.credits_remaining === "number") {
+    lastSnapshot.creditsRemaining = envelope.credits_remaining;
+  }
+  if (typeof envelope.tier === "string") {
+    lastSnapshot.tier = envelope.tier;
+  }
+  lastSnapshot.lastUpdated = Date.now();
+  lastSnapshot.lastError = null;
+}
+
+// Record a relay error (network failure, 5xx with no envelope, etc.).
+// Surfaced in the UI status so the user knows the balance display is stale.
+export function recordRelayError(message) {
+  lastSnapshot.lastError = (message || "Unknown relay error").slice(0, 300);
+  lastSnapshot.lastUpdated = Date.now();
+}
+
+export function getRelayState() {
+  return { ...lastSnapshot };
+}
+
+export function resetRelayState() {
+  lastSnapshot = {
+    creditsRemaining: null,
+    tier: null,
+    lastUpdated: null,
+    lastError: null,
+  };
+}