feat: encrypted account-level secrets (#501)

* feat: add encrypted account-level secrets with UI for adding API keys

Adds AccountSecret model with AES-256-GCM encryption, API routes for
CRUD, "Add secret" button in model costs section, and injects decrypted
secrets into action env (YAML secrets take precedence).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: repo secrets, sidebar icons, lazy learnings history

- add repo-level secrets with inheritance from org secrets
- add icons to console sidebar sections
- fix learnings history modal: lazy fetch with hover prefetch,
  strip content from list response, load content per-expansion

Made-with: Cursor

* add input validation bounds for secrets and fix client-side name filter

Made-with: Cursor

* refactor: migrate all client-side data fetching to TanStack Query

Replace manual useState/useEffect/fetch patterns and the custom
usePolling hook with useQuery, useInfiniteQuery, and useMutation
across the entire frontend for consistent caching, background
refetching, and reactive invalidation.

- ActiveWorkflowRunsSection: useQuery + refetchInterval
- WorkflowRunHistory: useInfiniteQuery + polling query
- LearningsSection: useQuery per revision (lazy)
- FlagsSettings: self-contained useQuery + useMutation
- SecretsCard: useMutation for delete
- AddWorkflowButton, VerifyWorkflowButton: useMutation
- EmailSignupForm, email-waitlist: useMutation
- providers.tsx: enable refetchOnWindowFocus
- Delete usePolling.ts (no remaining consumers)

Made-with: Cursor

* address PR review: squash migrations, rename accountSecrets → dbSecrets

Squash the two separate secrets migrations into a single migration.
Rename the wire format field from accountSecrets to dbSecrets since
it now carries merged account + repo secrets.

Made-with: Cursor

* fix: update proxyKeys.ts imports after cache.ts -> yes package migration

Made-with: Cursor

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

models.ts

@@ -93,7 +93,7 @@ export const providers = {
   }),
   google: provider({
     displayName: "Google",
-    envVars: ["GOOGLE_GENERATIVE_AI_API_KEY", "GEMINI_API_KEY"],
+    envVars: ["GEMINI_API_KEY", "GOOGLE_GENERATIVE_AI_API_KEY"],
     models: {
       "gemini-pro": {
         displayName: "Gemini Pro",