[IC-085] Standardize frontend API errors, correlation IDs, retries, and expired-session behavior.

[github-actions]

Outcome

Standardize frontend API errors, correlation IDs, retries, and expired-session behavior.

Acceptance checks

• Errors never leak raw server details; safe retry is limited to idempotent operations; support IDs connect to backend telemetry.

Dependencies

IC-070

Planning metadata

• Priority: P1
• Milestone: Milestone 8 — Frontend completeness and accessibility

Definition of done

• Automated tests cover the change where practical.
• Tenant/environment isolation and failure paths were reviewed.
• Logs and errors contain no secrets, PII, documents, or biometric data.
• Relevant API, architecture, operations, and user documentation is updated.
• The pull request links this issue and lists verification commands.
  Generated from docs/planning/implementation-backlog.md; edit the backlog and rerun the sync to change generated fields.