Implement tenant quotas and tenant-aware search, metrics, and limits

[niteshpurohit]

Summary

Implement stronger tenant-aware operational boundaries.

Scope

• tenant quotas and capacity controls
• tenant-aware search and metrics boundaries
• limits and visibility rules that reinforce tenant and namespace isolation

Acceptance Criteria

• tenant isolation is reflected in operator workflows, not just storage boundaries
• quotas and limits can be reasoned about explicitly
• tenant-aware visibility remains consistent across search, metrics, and operational controls