Fix repository searches for the string zero

[HarshMN2345]

Repository searches for the literal string 0 currently return unfiltered repositories because the adapters treat it as an empty search. Preserve the query for GitHub, Gitea, Forgejo, Gogs, GitLab, and Bitbucket while keeping an empty string as the request for all repositories.

The GitHub path filters selected installation repositories before pagination. Provider-backed searches now include 0 in the outbound query, including GitLab's personal-namespace fallback. Origin already preserves the value and requires no change.

Validation: 15 focused tests pass (17 assertions), covering zero and empty searches across providers and GitHub pagination. Eight regressions fail against the original adapters. The complete package unit suite passes: 103 tests, 394 assertions, one existing skip. bin/monorepo check vcs (Pint, PHPStan level 5, Rector), bin/monorepo validate, and git diff --check pass. Tests use local provider fakes and make no external requests.

CI passed package checks (Pint, PHPStan, Rector) and the complete unit suite: 103 tests, 394 assertions, one existing skip. Provider E2E tests did not start: the unchanged GitHub authentication preflight rejected the configured app identifier with HTTP 401 (errorCategory: issuer; the identifier was neither numeric nor a client ID beginning with Iv1.). CI credentials need correction before provider E2E validation can complete. Failed job log.

Appwrite must preserve the query at its API boundary and adopt a released package version before this behavior reaches Appwrite users. That consumer patch and Gitea API regression are prepared separately, pending dependency adoption.