fix(runtime): stabilize session and hook lifecycles

[CBEPX]

Summary

• route native hooks through a stable marketplace-specific ${PLUGIN_DATA} launcher so cache refreshes cannot strand running sessions on deleted version paths
• prefer live CODEX_THREAD_ID ownership, preserve marker fallback, and resolve exact job IDs across linked worktrees
• harden worker/reaper races, foreground review signal cleanup, and read-only Claude stream parsing diagnostics
• prepare the synchronized v1.6.1 patch release and stop writing the removed Codex plugin_hooks feature

Verification

• npm run check (770 unit, 100 integration, 22 E2E)
• npm run test:lifecycle-contract (12/12)
• npm run test:mutation:pr (82.65% critical, 74.69% managed, 66.39% installer)
• npm pack --dry-run --json
• Claude Code review via cc, Opus/xhigh
• independent Codex gpt-5.6-sol/xhigh review: no remaining P0/P1/P2 findings

Closes #16