Dashboard dev-fallback tightening: enforce authenticated endpoint usage in production

[ApexYash11]

Summary

Tighten dashboard data loading so production paths always use authenticated backend endpoints.

Why

Docs flag debug/dev fallback pathways as a security and reliability risk if boundaries are unclear.

Scope

• Audit dashboard fetch logic for dev fallback behavior.
• Gate fallback behavior to local/dev only (explicit environment checks).
• Enforce authenticated endpoint usage in production paths.
• Improve user-safe error messaging when auth/context is missing.

Acceptance Criteria

• Production dashboard path never uses debug/dev fallback data sources.
• Dashboard requests require valid auth context.
• Failures surface actionable error UI rather than silent degradation.

Source

• docs/SITE_FLOW_AND_IMPROVEMENTS.md (Improvement Plan deploy error fix #3)