docs(issue-5): phase 1 benchmark results, contract mapping, task checklist

Records the measured numbers and syncs every document that names the
delegation script paths, then bumps the framework to 4.3.0 in the three-way
lockstep (lib.sh, VERSIONS.md current + matrix, eight SKILL.md frontmatters).

phase1-benchmark.md carries both arms. The deterministic fake transport is what
CI asserts on: 50 publishes cost 50 connections one-shot and 1 persistent, p50
54.813ms -> 0.002ms. The real broker run is informational, since the PoC
default is a public broker: p50 1892.728ms -> 275.992ms, about 85% off.

It also corrects the plan's own estimate rather than repeating it. D8 predicted
the new shell path would drop from 3 forks to 2; the implementation is still 3,
because keeping the `_delegate_script publish_event.py` lookup is the only
thing that produces the "missing script tree does nothing" non-fatal contract
that C-02 pins. Saving that fork would change the contract, so it is deferred
to phase 4 rather than taken quietly.

SKILL.md gains the context table saying which tree wins where, so an operator
reading it knows a frozen loop runs frozen delegation code. The script paths in
every document remain correct and every quoted command still works verbatim.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UrDNJkHmm18uu7n7JwV5Qd

.agents/skills/multi-agent-mux-delegate-job/SKILL.md

@@ -1,7 +1,7 @@
 ---
 name: multi-agent-mux-delegate-job
 description: "Delegate a unit of work to any autonomous agent (claude-code, hermes, agy, grok-build, codex, or a human) and observe it asynchronously over an MQTT event channel. Supported roles include orchestrator, worker, and reviewer."
-version: 4.2.0
+version: 4.3.0
 author: godopu
 license: MIT
 platforms: [linux, macos, windows]
@@ -70,6 +70,31 @@ For detailed state machine diagrams and configurations, see [DELEGATION_TYPES.md
 
 ---
 
+## Where the Implementation Lives (v4.3.0)
+
+The implementation moved to the `lib_py.delegation` package in issue #5 phase 1.
+`scripts/{mqtt_common,registry,publish_event,job_subscriber}.py` remain as
+compatibility shims and **their paths are unchanged** -- every command in this
+document still works verbatim. Each shim binds the `lib_py.delegation` package
+to the tree next to itself, once per process, without touching `sys.path`, so
+`import mqtt_common` yields the same module object as
+`lib_py.delegation.mqtt_common`.
+
+Which tree wins, by execution context:
+
+| Context | Resolved by | Tree that wins |
+|---|---|---|
+| Loop process and its children (frozen `lib.sh` sourced) | `PYTHONPATH` | the frozen snapshot |
+| Agent session running a **frozen** script path while `PYTHONPATH` still points live | the shim, from its own location | the frozen snapshot (B-13 preserved) |
+| Live helpers (create/stop/resume/reconcile) | `PYTHONPATH` or the shim (same tree) | the live tree |
+| Standalone, no `PYTHONPATH` | the shim's fallback append | the shim's own tree |
+
+`lib.sh` calls the package through `python -m lib_py.delegation.cli`. Setting
+`MAM_DELEGATION_PY=0` switches the shell helpers back to their preserved legacy
+bodies with no redeploy.
+
+---
+
 ## The Event Protocol Contract
 
 Every agent participating in the delegation contract must follow the same lifecycle publishing protocol using `publish_event.py`: