chore(web): remove dead front-end code left by the Foldkit migration - #2449

🟢 Confidence 10/10 · safe to merge. Dead-code deletion only: every removed export name has no reference at the head SHA, and no live caller changed.
_{no findings · tests not needed · risk medium}

Removes unreferenced front-end code across apps/web, packages/ui and packages/web-data, plus a stale Vite flag, and adds three missing define keys. I grepped every removed name at the head commit and found no remaining user, so it is safe to merge.

• Removes ~70 unreferenced *.styles.ts constants and dead helpers from packages/ui
• Drops toWhereClause, identityFromKey and factoryLinks; tests now call the live helpers instead
• vite.config.ts define list gains VITE_CLERK_SIGN_IN_URL, VITE_CLERK_SIGN_UP_URL and VITE_MCP_URL
• Retires the VITE_MAPLE_CAPTURE flag and its requireConsent branch in platform/telemetry.ts

Before merge

• Manual · Confirm VITE_CLERK_SIGN_IN_URL, VITE_CLERK_SIGN_UP_URL and VITE_MCP_URL are set in the prd and dev deploy env, since they are now baked into the bundle

_{8d3f920 · Reply "won't fix" to dismiss a finding, or mention @maple-review-bot to ask about one.}