🛞 feat: Manage Personal Code Environment Lifecycles (#15369)

* feat: add self-service code worker pairing

* fix: enforce code worker principal boundaries

* fix: separate pairing control planes from execution

* fix: preserve principal worker routing

* fix: pin artifact traffic to code workers

* fix: authenticate code worker selection

* test: mock worker-aware artifact headers

* fix: harden self-service code worker routing

* fix: fail closed for principal code pairing

* feat: manage personal code environments

* fix: harden personal code environment lifecycle

* fix: satisfy backend lifecycle types

* fix: harden principal environment lifecycle and quotas

* fix: fence environment lifecycle races

* fix: reconcile code environment stack

* style: format code execution headers

* fix: reconcile code environment lifecycle

* fix: close self-service pairing gaps

* fix: close code environment reconciliation gaps

* fix: close code environment UI review findings

* fix: satisfy code environment type checks

* fix: route code priming to selected worker

* fix: harden code environment lifecycle fences

* fix: type lease renewal interval

* fix: harden environment lifecycle recovery

* fix: close lifecycle recovery races

* fix: type compensated agent timestamps

* fix: fence lifecycle cleanup by tenant and revision

* fix: scope environment revision fencing