Use REM for the first comment line of each batch script

[dmccoystephenson]

Summary

• The first line of up.bat, down.bat and create_environments.bat is changed from a # line to a REM line. cmd.exe has no # comment syntax, so each of these lines was being run as a command named #, printing a "not recognized as an internal or external command" error at the start of every run. Every other comment in the scripts already uses REM.
• tests/test_batch_scripts.py is added as a regression guard: it reads the three scripts as text and fails if any line starts with #. It needs no Windows, and the README's test section mentions it.
• The module docstring of headless_run.py now states the exit status 2 for invalid arguments, which the code (sys.exit(2)) and the README already describe; the docstring previously listed only 0 and 1.

The cycle was run as a documentation accuracy sweep (the open backlog being gated or large, see below). The README, the batch scripts and the CLI argument handling in main.py and headless_run.py were checked against source; apart from the items above, no drift was found.

Closes #37

Test plan

• python -m py_compile of every top-level module passes
• python3 -m unittest discover -s tests — 123 tests ran, OK (Python 3.8.10, pygame 2.1.2)
• The new test was run against the pre-fix scripts (git checkout origin/main -- *.bat) and failed for all three, then passed with the fix restored
• python3 headless_run.py — all three scenarios PASS
• python3 headless_run.py x exits with status 2, matching the updated docstring
• The batch scripts could not be run, since no Windows cmd.exe is available in the environment the change was made in; the fix rests on REM being the documented cmd.exe comment command and on the scripts' existing REM lines. Running up.bat once on Windows and confirming no '#' is not recognized line appears would verify it.

Deferred issues

• Decide whether per-location colours should be stable across frames #24 (stable per-location colours) — gated on an owner decision between stable and animated colours, which an autonomous run cannot make.
• Add text-based UI support to library for users #11 (text-based UI support) and Support drawing environments with multiple grids #2 (multiple grids) — feature work too large for one polish-sized PR, with no design settled in the issues.

This PR description was drafted during a Gardener session (https://github.com/Stephenson-Software/gardener).

🤖 Generated with Claude Code

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drafted by Claude on behalf of Daniel Stephenson

[dmccoystephenson]

Self-review rubric (head b720b7d):

• Scope: PASS, with one judgment note. The three .bat edits and tests/test_batch_scripts.py serve Batch scripts start with '#' lines, which cmd.exe runs as a command #37 directly. The headless_run.py docstring line and the one-sentence README addition are not covered by Batch scripts start with '#' lines, which cmd.exe runs as a command #37: the first is the documentation-sweep finding stated in the PR body, and the second documents the new test. Both are small and declared, but they sit outside Closes #37.
• Tests-new: PASS. No new public function is added; the new test file covers the changed scripts.
• Tests-fix: PASS. Checked empirically: with up.bat, down.bat and create_environments.bat checked out from origin/main, python3 -m unittest tests.test_batch_scripts gave FAILED (failures=3) ([1] != [] for each script). With the fix restored it passed.
• Sibling structure: PASS. tests/test_batch_scripts.py follows the existing tests/test_*.py files: stdlib unittest, one TestCase class with a docstring naming the issue it guards (as TestConstruction in tests/test_graphik.py does for Graphik defines __init__ twice, so the no-argument constructor is dead code #20), and no __main__ block.
• Sibling renames: PASS. Nothing is renamed.
• Docs: PASS. The README's batch-script commands and create_environments.bat description are unchanged and still match the scripts. The test section of the README now mentions the new test. The headless_run.py docstring now matches sys.exit(2) and the README.
• Issue resolution: PASS. All three # lines named in Batch scripts start with '#' lines, which cmd.exe runs as a command #37 are now REM lines, and no #-prefixed line is left in any of the scripts (checked by the new test).
• Manual validation: PASS for what can run here. py_compile is clean, 123 unit tests ran and passed, and headless_run.py passed all three scenarios. CI Tests passed on b720b7d. The batch scripts themselves are UNVERIFIED-not-applicable: no cmd.exe is available, and none of the rendering or Viron-service files that the live anchor checks are touched.

Observations outside the diff:

• create_environments.bat and the other scripts are committed with LF line endings, and create_environments.bat relies on goto loop. cmd.exe label lookup is known to misbehave in some cases with LF-only files. This is not addressed here and has not been reproduced.
• create_environments.bat:28 sets log_file, which is never used.

Summary: a small, contained fix with an empirically confirmed regression guard. No blocking findings.

This review was drafted during a Gardener session (https://github.com/Stephenson-Software/gardener).

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drafted by Claude on behalf of Daniel Stephenson