fix(page_package): prefer the package found in the working dir

[LukasGold]

Closes #135

Changes

• New find_first_package_dir, which walks the search paths in order and returns the first match, or None
• Both lookups in PagePackageController.check_required_pages use it: package info dirs and package creation scripts
• find_package_dir is untouched, so its all-at-once semantics stay available
• tests/test_page_package_search.py covers search order, fall-through to a later path, no match, file matches as well as directory matches, and that find_package_dir still rejects ambiguity

Rationale

The old calls passed all search paths to find_package_dir at once. That function collects matches across every path and raises ValueError when there is more than one, so a package present both in the working dir and in an additional_package_dirs entry failed instead of resolving to the local one.

The script branch had the same shape and the same latent bug, with script_dir and additional_script_dirs. Both are fixed here rather than split across PRs, since it is one bug in two places.

Follows the approach proposed in the issue. A path holding several matches on its own is still ambiguous, so it is skipped with a warning rather than guessed at.

Behaviour change worth noting

Previously a lookup that found nothing was swallowed by the broad except Exception and reported as "Error reading package info". Now a missing package and a broken package are two distinct warnings, and a failure to read a package that was found no longer falls through to a lower-priority copy of the same name.

[github-actions]

Release preview

Merging this PR would release v2.0.3 (current: v2.0.2).

Changelog preview (truncated)

## v2.0.3 (2026-09-01)

### Bug Fixes

- **page_package**: Apply the same search order to package scripts
  ([`751a0e3`](https://github.com/OpenSemanticLab/osw-python/commit/751a0e3df80000e639349401b29a6ed311fb5f69))

- **page_package**: Prefer the package found in the working dir
  ([`6e58d9e`](https://github.com/OpenSemanticLab/osw-python/commit/6e58d9ea1fe9067326571356ef8de736c7938ab2))

### Testing

- Rename oold.py to oold_test.py so its tests are collected
  ([`20072a9`](https://github.com/OpenSemanticLab/osw-python/commit/20072a9249cd97126a222c62a70f84e0433343ef))

_{Preview via python-semantic-release and conventional commits.}