refactor(self-mod): drop request_rebuild — approvals now bundle rebuild+restart

install_packages and add_mcp_server already did the right thing on approve
(install auto-rebuilt+killed, add_mcp_server just killed), so request_rebuild
was redundant plumbing agents sometimes called after an install — wasting an
admin approval round-trip. Delete it end-to-end:

- container/agent-runner/src/mcp-tools/self-mod.ts: remove requestRebuild
  tool + registration; update install_packages description.
- src/modules/self-mod/{request,apply,index}.ts: drop handleRequestRebuild
  + applyRequestRebuild + registrations; rewrite the rebuild-failed notify
  to point admins at retrying install_packages instead.
- src/modules/{approvals,self-mod}/{agent,project}.md and skill/self-
  customize/SKILL.md: scrub agent-facing references; clarify that
  add_mcp_server needs no rebuild (bun runs TS directly).
- docs/{module-contract,architecture-diagram,checklist,db-central,shared-
  source,v1-vs-v2/*}.md, CLAUDE.md, pending-approvals migration comment,
  approvals/index.ts docstring, REFACTOR.md: trailing references.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/module-contract.md

@@ -66,7 +66,7 @@ export function registerDeliveryAction(action: string, handler: ActionHandler):
 
 **Default when action is unknown:** log `"Unknown system action"` at `warn` and return. Message is still marked delivered (it was consumed by the host, not sent to a channel).
 
-**Current consumers:** scheduling (5 actions — `schedule_task`, `cancel_task`, `pause_task`, `resume_task`, `update_task`), approvals (3 actions — `install_packages`, `request_rebuild`, `add_mcp_server`), agent-to-agent (`create_agent`, and the agent-routing branch keyed as a pseudo-action `agent_route`).
+**Current consumers:** scheduling (5 actions — `schedule_task`, `cancel_task`, `pause_task`, `resume_task`, `update_task`), approvals (2 actions — `install_packages`, `add_mcp_server`), agent-to-agent (`create_agent`, and the agent-routing branch keyed as a pseudo-action `agent_route`).
 
 ### 2. Router sender resolver + access gate