#4097 refactor: extract command runtime package

Summary

Extract execution and command binding into private @agent-device/command-runtime, with one entry and explicit named exports. The daemon retains its three-family surface; contact-sheet execution stays lazy. Released CLI, Node, and MCP interfaces are preserved. Related: #3276.

Scope: 185 files, predominantly source/test renames. The artifact adapter moves to host-kit while preserving the published root IO facade. CLI handlers now load its implementation owner directly. Contract tests use the real default session store. Review fixes preserve path handling and rename provenance on synthetic PR merges. The root-zone comment states the published facade constraint.

Validation

Tested head: f30bf1de26cff40538dda6aae03883928d3106cf.

• pnpm check:affected --run --base 754a0b71e77c4cf9398210c597909f746e5ac4e1 --head f30bf1de26cff40538dda6aae03883928d3106cf: passed (run-lMK3tC, exact unchanged commit), including build, integration and unit checks. The prior adapter-import delta passed run-bPAkAt. Clean merge-tree against main.
• At 0f490467e7, the full affected gate passed (run-dRiUbM), and pnpm gate mutation --modules kernel-errors --shard 4/5 completed: 5,041 dry-run tests, 438 owned files, 80 mutants, no timeouts or errors. GitHub's previously failing shard also passed there. The fixture avoids repeated host probes during virtual time while retaining real child exit and deadline checks; the original CI timeout cause remains unproven.
• Android smoke remains attributed to ef02bc1f. Fresh GitHub checks and configured reviews are required at the new head. Adapter containment remains lexical.