[txltedxgod]

Summary

Closes #144

Consolidates the three independent implementations of 'format template + write' onto \write_starter_config\ and ensures all starter-config writes are atomic:

1. Atomic starter creation: \write_starter_config\ now writes via \write_text_atomic\ (temp file in same directory + \os.replace), preventing corrupted/truncated .profiles\ files on interrupted --init\ or creation prompts.
2. Consolidated delegation:
   • \profiles.app.init_default_config\ delegates directly to \write_starter_config.
   • \profiles.core.config.loader.propose_config_creation\ delegates directly to \write_starter_config.
   • \profiles.launch.creation.propose_creation\ (and the /api/config/create\ endpoint) continues delegating to \write_starter_config.
3. Custom \cwd\ parameter: \write_starter_config\ now supports an optional \cwd\ keyword argument (defaulting to \Path.cwd()) for template placeholder substitution.
4. Test coverage:
   • Added \ est_uses_atomic_write\ and \ est_writes_with_custom_cwd\ to \ ests/core/test_actions.py.
   • Added \ est_delegates_to_write_starter_config\ to \ ests/test_app.py.
   • Updated \ est_write_error_returns_false\ in \ ests/core/config/test_loader.py\ to verify atomic writer error handling.

All 227 configuration and creation tests pass cleanly.

[falbany]

Thanks for this — clean consolidation, and making write_starter_config the single atomic writer is exactly what #144 called for. I've verified locally on your branch (3c2011e): 1521 tests pass, coverage 88.93%, pylint 9.88, pyright clean, and the logic reviewed well (the lazy profiles.core.actions import in loader.py avoids circularity, and the test mocks land correctly).

Two small things before merge:

1. ruff format now runs as a CI gate (see .github/workflows/ci.yml, added today). Your branch has one violation: a missing blank line at tests/test_app.py:578 (after the from profiles.core.actions import ... line). Just run ruff format tests/test_app.py.

2. Please rebase onto (or merge in) latest main — CI/Linux portability fixes landed in tests/core/test_actions.py, the same file this PR touches, and it's good to validate against the new quality gates.

Everything else looks good; no other changes requested. One non-blocking note: write_text_atomic uses mkstemp, so newly created .profiles files get 0600 permissions instead of umask defaults — arguably an improvement for a config file, just flagging the delta.

[txltedxgod]

Thanks for the review @falbany! Addressed both items on d14e065:

1. Ran ruff format on tests/test_app.py (ruff format --check . now reports all 223 files formatted, ruff check . clean).
2. Rebased cleanly onto main (7c1e949).

Both Quality gates (Python) and Web front-end (build & tests) checks have passed on the updated branch (Windows packaging dry-run is still running).