Implement functional acceptance test suite with intent annotations

[arcavenai]

Summary

Build a repeatable acceptance test suite from the test battery documented in #20. These are not unit tests — they verify the installed binary on real hardware from a user's perspective.

What we need

A test runner (shell script, justfile recipe, or both) that:

1. Runs scripted tests — automated assertions with pass/fail output
2. Annotates each test with intent — what it verifies, why it matters, what issue it traces to
3. Flags manual-only tests — describes expected behavior for a human or AI agent to evaluate
4. Reports results — summary of pass/fail/skip with enough context to diagnose failures

Test groups (from #20)

1. Self-update — version identity, update cycle, channel filtering
2. Session lifecycle — start, list, status, detach/reattach, stop
3. Control session behavior — single vs multi, sharing, cleanup
4. Session content — aclaude launches in correct pane, persona voice
5. One-shot prompt — text vs JSON output
6. Configuration — config display, persona list
7. tmux-cmc protocol — debug trace, tcgetattr regression

Design principles

• Dual-layer: Each test has an intent description (human/AI-readable) and a script (executable). The intent layer explains why this test exists and what a failure means. The script layer runs the check.
• Regression anchors: Every test links to the issue that created it. If a test fails, the issue tells you the full debugging history.
• Two audiences: An AI agent running these tests should be able to read the intent, run the script, and make a judgment call on whether the result is acceptable — especially for subjective tests (TUI rendering, persona voice).
• Portable: Must run on the target hardware (aarch64 Raspberry Pi, tmux 3.5a, no sudo, no image protocol). No dependencies beyond bash and the aclaude-a binary.

Suggested location

tests/
  acceptance/
    run.sh              # test runner
    01-self-update.sh
    02-session-lifecycle.sh
    03-control-sessions.sh
    04-session-content.sh
    05-one-shot-prompt.sh
    06-configuration.sh
    07-tmux-cmc-protocol.sh

Or as justfile recipes:

just test-acceptance          # run all
just test-acceptance-update   # group 1 only
just test-acceptance-session  # group 2 only

Reference

Full test battery with scripts and intent annotations: #20