When importing issues, if an incoming issue has the same content hash as an
existing issue but a DIFFERENT prefix, this should not be treated as a rename.
Cross-prefix content matches occur when importing issues from other projects
that happen to have identical content.
Previously, the importer would call handleRename which tries to create an issue
with the incoming prefix, failing prefix validation ("does not match configured
prefix" error).
The fix checks if prefixes differ before calling handleRename:
- Same prefix, different ID suffix → true rename, call handleRename
- Different prefix → skip incoming issue, keep existing unchanged
Added test: TestImportCrossPrefixContentMatch reproduces the bug scenario
where alpha-* issues exist but beta-* issues are imported with same content.
627ac1afb8