fix(mcp): resolve index_repository's repo_path from a known project name

[AmirF194]

What does this PR do?

handle_index_repository requires repo_path and errors with "repo_path is required" when it is absent. list_projects only ever advertises the project NAME, never repo_path, and every read tool accepts that name back through get_project_arg's project/project_name/project_id/projectName aliases (mcp.c:1385), but index_repository did not, so re-indexing an already-indexed project by the name list_projects gave you had no resolution path and failed immediately, even though the project's root was already on file.

Fix: added resolved_repo_path_from_project_arg(), a query-only lookup of the project's own stored root_path, tried when repo_path is absent before giving up. It never touches srv->store or srv->current_project, so it cannot disturb whatever project the server already has cached, and an unresolvable name still falls through to the original, correct "repo_path is required" error.

Verified in a clean ubuntu:24.04 container (TEST_SUITES=mcp make -f Makefile.cbm test-focused):

• New test tool_index_repository_resolves_root_path_from_project_name_issue1211 fails on unpatched main (strstr(resp, "repo_path is required") is not NULL) and passes with the fix.
• Companion test tool_index_repository_unknown_project_name_still_requires_repo_path guards the fallback: a name with no stored project still gets the exact original error, not a resolver crash or silent no-op.
• Full mcp suite: 179 passed on both sides, one pre-existing, unrelated failure (tool_detect_changes_contained_commands_clean_up_error_and_success, test_mcp.c:5814) reproducing identically on unmodified origin/main, so not introduced by this change.
• scripts/lint.sh --ci CLANG_FORMAT=clang-format-20 and scripts/security-audit.sh both clean.

Refs #1211 (this PR fixes only the repo_path-required/name-resolution bug the issue was filed for; a separate, unrelated defect was reported in the thread afterward: CBM_ALLOWED_ROOT refusals get mis-reported as a worker crash. Leaving the issue open rather than auto-closing it on merge.)

Checklist

• Every commit is signed off (git commit -s)
• Tests pass locally (make -f Makefile.cbm test, focused on the mcp suite)
• Lint passes (make -f Makefile.cbm lint-ci)
• New behavior is covered by a test (reproduce-first for bug fixes)

[DeusData]

Thank you for the contribution and for isolating the list_projects and index_repository mismatch with regression coverage. This is now triaged as a 0.9.1-rc integration bug at normal priority. Our community PR queue is currently quite full, so it may take a little time before we can complete the review and, if approved, merge it. We are doing our best to support community contributions and will return with code-grounded feedback as capacity opens.

[AmirF194]

Thanks for the update, no rush. Happy to adjust the fix if the 0.9.1-rc review turns up anything.