Add Link wallet support with Eve 0.66.3

[fmhall]

Adds Link wallet connection and purchasing through the official Eve extension, pinned to Eve 0.66.3 and @stripe/link-integrations-eve 0.2.4.

Existing phone users connect Link from /link, linked from workspace Connections. Better Auth stores encrypted OAuth grants, refreshes them under a database lock, and revokes them on disconnect. Link configuration remains optional for deployments; the setup page explains the required environment variables and callback URL.

For browser purchases, the coordinator creates and checks a Link spend request through the extension, then passes its approved ID to the browser worker. The worker retrieves card details server-side, checks caller and browser ownership, current approval, merchant origin, amount, currency, and expiry, and uses the existing Kernel-backed Chromium autofill. Its result contains only a receipt. The coordinator's retrieval override omits credential expansion, and both agents have instructions for approval, continuation, submission, and uncertain outcomes. Payment fills no longer automatically retry another control after an error.

Review the OAuth ownership and refresh boundary, status-only extension override, and worker checks before card injection. The browser bridge currently supports one-time card forms on the approved merchant origin. Cross-origin payment frames, recurring requests, Shared Payment Tokens, and Link Pay Tokens are unsupported. Autofill completion is not evidence that an order succeeded.

Validation:

• pnpm check — 764 tests across 88 files; lint, type checking, formatting, and Knip passed.
• DATABASE_URL=postgresql://postgres:postgres@127.0.0.1:54329/open_instinct KERNEL_API_KEY=build-only BETTER_AUTH_URL=http://localhost:3000 pnpm build — passed.
• pnpm exec eve build --skip-sandbox-prewarm — passed; compiled output selects the status-only override and worker fill tool.
• Independent read-only review of the browser composition change — no actionable findings.

Link HTTP and browser CDP boundaries are mocked in regression tests. No live Link payment was performed; local Link OAuth credentials are not configured. Sandbox image prewarming was skipped.