Make install.sh run unattended and survive a reinstall

[dmccoystephenson]

Summary

• install.sh now starts with #!/bin/sh and set -e, so it names its shell and stops at the first failed step. Before this change, if the git install was declined, /bin/fishe was still written and pointed at a directory that was never cloned.
• /usr/games is created with mkdir -p, so the File exists error no longer appears on Debian/Ubuntu, where the directory is normally present already.
• apt-get install -y git removes the confirmation prompt that stopped non-interactive runs.
• If /usr/games/FishE/.git already exists, the clone is updated with git -C … pull and not cloned again, so the script can be run a second time.
• tests/test_installScript.py checks these points by reading the script's text, following the approach in tests/test_shellEntryPoints.py. The script needs root and changes /usr/games and /bin, so neither the suite nor CI can run it.
• The install line in the README now says the script runs without prompting and can be run again.

Closes #205

Test plan

• Full suite run under the dummy SDL drivers (in-process os.environ + pytest.main): 923 passed
• With install.sh stashed back to main's version, all 5 new tests fail. With the change restored, they pass.
• sh -n install.sh returns 0
• Not verified: the script was not run end to end as root on a real Debian host. No automated coverage exists for that path, so a first install followed by a reinstall on a scratch VM is recommended before relying on it.

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 (CI run 36687265692 green on the PR head):

• Scope: PASS. There are three files: install.sh (the fix), tests/test_installScript.py (its tests), and one README sentence describing the new behavior. No unrelated churn is included.
• Tests-new: PASS. No new public functions were added. Each of the four points in install.sh: stops at an apt prompt, errors on an existing /usr/games, and fails on reinstall #205 (shebang, set -e, mkdir -p, apt-get -y, the existing-clone branch) has its own test.
• Tests-fix: PASS. With install.sh stashed back to main's version, all 5 tests in tests/test_installScript.py failed. After git stash pop, they all passed.
• Sibling structure: PASS. The new test file follows tests/test_shellEntryPoints.py: a module docstring stating the contract, a REPOSITORY_ROOT file reader, comment-stripping so a comment can't satisfy a test, and # prepare / # call / # check.
• Sibling renames: PASS. No renames.
• Docs: PASS. README.md:27 now says the script runs without prompting and can be run again. No schema, PLANNING.md or version change is needed for an installer-only change.
• Issue resolution: PASS. Every item listed in install.sh: stops at an apt prompt, errors on an existing /usr/games, and fails on reinstall #205 is changed in install.sh.
• CI: PASS. test is green (923 tests locally, full suite in CI).
• Schema-sync / Money-format / Deterministic-tests / Headless-pygame: not applicable. No persisted field, money display, randomness or pygame path is touched.
• camelCase: PASS. The helpers are readInstallScript and commandLines.

Notes:

• install.sh:14 — the existing-install check looks for $INSTALL_DIR/.git. If /usr/games/FishE exists but is not a clone, git clone still fails, and set -e now stops the script before /bin/fishe is written. This is the intended behavior: a directory that is not a clone is not overwritten.
• Coverage gap: CI cannot run install.sh, since it needs root, apt and writes to /bin. The tests check the script's text, not its behavior. sh -n install.sh passes. A real first install followed by a reinstall on a Debian host is still recommended.
• Out-of-diff finding, filed separately: run.sh's first line is # /bin/bash, a comment and not a shebang, and the script uses the bash-only &>. Under dash, if ! command -v python3 &> /dev/null takes the "Python could not be found" branch even when Python is installed. This was reproduced with dash -c. It is outside install.sh: stops at an apt prompt, errors on an existing /usr/games, and fails on reinstall #205's scope.

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