Mission Control: 5-wide integration PR (auth readiness, perf fixtures, observability, presence, launch-gate auth split)

[krusty-agent]

This PR consolidates the 5 parallel fast-lane branches into one integration PR.

Included lanes/commits:

• Auth readiness hardening for seeded e2e auth envs and explicit skip reasons
• AC5 perf fixture hardening + production-sized seeded path
• Observability routing/provisioning parity validation hardening
• Presence dedupe + expired-session pruning + tests
• Launch-gate readiness drill auth split (API key vs JWT routes)

Validation highlights (from lane runs):

• mission-control observability validation passes
• perf fixture tests pass (3/3)
• presence session tests pass (3/3)
• e2e suite compiles/lists with updated AC5 harness

Notes:

• This is a consolidation PR; prior slice PRs remain open for traceability and can be closed/superseded after review.

[krusty-agent]

Superseded by consolidated PR #167: #167