feat(bridge): add KYC tier ceiling error code (ENG-354)

[patoo0x]

Summary

Adds a distinct BRIDGE_KYC_TIER_CEILING_EXCEEDED GraphQL error code for when Bridge rejects a withdrawal because the amount exceeds the user's KYC-tier cap.

Changes

• src/services/bridge/errors.ts: Added BridgeKycTierCeilingExceededError class + detection in mapBridgeHttpError for Bridge API 422/400 responses containing KYC tier ceiling errors
• src/graphql/error-map.ts: Mapped BridgeKycTierCeilingExceededError → BRIDGE_KYC_TIER_CEILING_EXCEEDED
• **docs/bridge-integration/API.md: Added error code to the table
• **test/flash/unit/graphql/bridge-error-map.spec.ts: Added GQL mapping test for the new error + 5 mapBridgeHttpError detection tests

Verification

• 37 bridge error-map tests pass
• 3 bridge contract tests pass
• Prettier clean
• yarn check:sdl clean
• No schema regeneration needed (error mapping only)

[linear]

ENG-354