Clarify web build cooldown errors

[halfaipg]

Summary

• show human-scale retry guidance for 429 build cooldowns
• point real 402 plan-limit responses to codebase usage instead of the retired OAuth-gate diagnosis
• refresh compatible transitive dependencies to clear the production audit

Verification

• npm ci
• npm run check: 1293 tests passed
• npm run build
• npm audit --omit=dev: 0 vulnerabilities