chore(scaffoldia/repo-batcher): drop uninitialized template scaffolds

repo-batcher/src/abi/ and repo-batcher/ffi/zig/ were uninitialized template
scaffolds ({{project}} placeholders never substituted). Missed in the initial
scaffoldia absorption commit; this closes it.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: hyperpolymath