#1036: fix path for listing public repositories

[bibonix]

@yegor256 this PR fixes #1036.

Bug

Repos#iterate(String) (implemented by RtRepos) is documented to call the GitHub "List all public repositories" endpoint (/repositories?since=...), but it was issuing the request against the API root: /?since=.... As a result, GitHub returned the JSON object describing the API root rather than the expected JSON array, and RtPagination failed with javax.json.JsonException: Cannot read JSON array, found JSON object.

Fix

Add the missing /repositories path segment in RtRepos#iterate:

this.entry.uri().path("/repositories").queryParam("since", identifier).back()

Commits

1. #1036: regression test asserting /repositories path adds RtReposTest#iterateReposUsesPublicRepositoriesPath, which intercepts the outgoing request and asserts the URI ends with /repositories?since=<id>. Verified to fail on master and pass with the fix applied.
2. #1036: prepend /repositories path in RtRepos#iterate is the one-line fix.

Build status

• mvn -DskipITs test passes locally (717 tests, 0 failures).
• mvn -Pqulice install reports the same 837 PMD violations that already exist on master (e.g. PR #1168: handle JSON null in User.Smart#name() and #hasName() #1851 was merged with the identical mvn (ubuntu-24.04, 24) failure). I confirmed locally that this branch produces exactly the same 837 violations as master — i.e. this PR does not introduce any new qulice violations.