🤖 fix: clarify run_and_report output handling guidance (#42)

Summary
Updated AGENTS.md to explicitly forbid wrapping, redirecting, piping,
prepending, or appending output when invoking `run_and_report`. This
keeps helper step markers readable in the Mux UI.

Background
The helper already handles logging, context control, and pass/fail
marker output. Additional shell wrapping around its output makes human
review harder in the Mux UI.

Implementation
- Added a direct instruction under **Mux Tooling Helpers** to invoke
`run_and_report` directly with no output wrapping.
- Added a matching **Anti-patterns** entry to reinforce the same rule in
a second high-signal section.

Validation
- `run_and_report verify-vendor make verify-vendor`
- `run_and_report test make test`
- `run_and_report build make build`
- `run_and_report lint make lint`

Risks
Low risk. This is guidance-only documentation and does not change
runtime behavior.

---

_Generated with [`mux`](https://github.com/coder/mux) • Model:
`openai:gpt-5.3-codex` • Thinking: `xhigh` • Cost: `$0.39`_

<!-- mux-attribution: model=openai:gpt-5.3-codex thinking=xhigh
costs=0.39 -->

Author: ThomasK33

AGENTS.md

@@ -87,6 +87,7 @@ Run from repository root.
 - `.mux/tool_env` is sourced before every `bash` tool call (Mux docs: `/hooks/tools`).
 - Use `run_and_report <step_name> <command...>` for multi-step validation in one bash invocation.
 - The helper writes full logs to `/tmp/mux-<workspace>-<step>.log`, prints pass/fail markers, and tails failures.
+- Do not pipe, redirect, prepend, append, or otherwise wrap `run_and_report` output. Invoke it directly so the helper’s step markers remain human-readable in the Mux UI.
 - Example:
   - `run_and_report verify-vendor make verify-vendor`
   - `run_and_report test make test`
@@ -113,6 +114,7 @@ Run from repository root.
 - Unpinned GitHub Action versions in workflow files (CI uses SHA-pinned actions).
 - Running CI-sensitive commands without vendoring mode when behavior differs from CI.
 - Removing assertion messages that start with `assertion failed:`; these are deliberate diagnostics.
+- Wrapping `run_and_report` output with shell redirection/pipes or extra surrounding text; this obscures the helper’s built-in markers in the Mux UI.
 
 ## Code Style