fix(p2p-15): harden runtime service lifecycle (#671)

[jlon]

Summary

• Finish runtime hardening in the P2P service after adaptive behavior lands.
• Keep scope inside service lifecycle and runtime policy handling; exclude telemetry and rollout assets.

Design

• Treat whitelist updates, listener generations, and ticket scoping as runtime-safety concerns.
• Lock the highest-value regressions with a compact end-to-end suite instead of broad harness growth.

Implementation

• Harden tenant whitelist runtime updates, listener restart/stop generation safety, and request-context ticket scoping.
• Add a compact p2p_e2e_test slice covering service lifecycle, negative provider cache, and provider rediscovery.

Verification

• Run targeted runtime-service tests.
• Run the compact core p2p_e2e_test suite.

[chatgpt-codex-connector]

Codex usage limits have been reached for code reviews. Please check with the admins of this repo to increase the limits by adding credits.
Credits must be used to enable repository wide code reviews.