Add test coverage for FishE.play() and error-recovery paths

[dmccoystephenson]

Summary

• src/fishE.py's core game loop (play()) had zero test coverage — every line inside it (location transitions, milestone announcements, eviction messages, goal announcement, per-tick save) was unexercised.
• Added coverage for loadStats/loadTimeService corrupt-file recovery, save()'s missing-data-directory creation and write-failure handling, and the __init__ path that loads timeService.json when present (previously only the "file absent" branches were tested).
• Coverage-only change: no production code modified. src/fishE.py line coverage goes from 77% to 99% (the remaining 2 lines are the if __name__ == "__main__": entry point, which isn't unit-testable).

Full backlog note: the repo's one open issue (#122, whether the stale PLANNING.md GOALS bait-price note should be deleted) requires the repo owner's memory of the original symptom to resolve safely, so it's intentionally left open/deferred rather than acted on this cycle.

Test plan

• python3 -m compileall -q src
• SDL_VIDEODRIVER=dummy SDL_AUDIODRIVER=dummy python3 -m pytest — 402 passed
• pytest --cov=src --cov-report=term-missing — src/fishE.py 77% → 99%, repo total 95% → 96%

[dmccoystephenson]

Self-review rubric:

• Scope: PASS — only tests/test_fishE.py changed (gh pr diff 130 --name-only); no production code, formatting, or unrelated files touched.
• Tests-new: PASS — every new test targets a line range that was uncovered before this PR (confirmed via pytest --cov=src --cov-report=term-missing): play() (lines 195-227, previously 0% covered), loadStats/loadTimeService exception paths, save()'s missing-directory creation and write-failure handling, the __init__ path that loads timeService.json when present, and the delete/quit branches of _selectSaveFile/_deleteSaveFile.
• Tests-fix: N/A — this is a Stage B test-expansion cycle (no production bug fixed), so there's no fix to stash/re-verify against.
• Sibling structure: PASS — new tests follow the file's existing # prepare / # call / # check comment structure and createXxx() factory-helper pattern (e.g. createGameForPlay() mirrors createGameForPersistence()).
• Sibling renames: N/A — no renames in this PR.
• Docs: PASS — no user-facing or persisted behavior changed; nothing in the README/schemas/PLANNING.md needs updating for a test-only PR.
• Issue resolution: N/A — no Closes #N. The repo's only open issue (PLANNING.md's only GOALS entry (bait price loading bug) may be stale #122) needs the repo owner's memory of the original bait-price symptom to resolve safely and is explicitly deferred (noted in the PR body), not something this cycle can close.
• CI: PASS — green on head commit fb46751 (https://github.com/Stephenson-Software/FishE/actions/runs/30344964561).

Repo-specific:

• Schema-sync: N/A — no persisted fields added/changed.
• Money-format: N/A — no new money/price display.
• Deterministic-tests: PASS — no new test depends on unseeded random.
• Headless-pygame: N/A — no pygame code path touched.
• camelCase: PASS — new identifiers (createGameForPlay, etc.) match the file's existing camelCase convention.

Net effect: src/fishE.py coverage 77% → 99% (only the untestable if __name__ == "__main__": entry point remains uncovered); full suite 402 passed.