Avoid unsynced warning for configured trailing-slash source #63

The PR #61 verification fixture lists intelligence/rules/ in sources.rules. Plain sync renders its rule correctly and sync --check --force exits 0, but the check emits WARNING: NOT SYNCED: intelligence/rules and recommends wiring the source again.

Reproduced by the independent verifier at a209d67 using the runnable Verification fixture in #61. The discovery diagnostic treats the configured trailing-slash spelling as different from the discovered directory. Normalize both sides with the existing source-path convention and add a regression asserting the false diagnostic is absent.

This is a diagnostic follow-up: the source is rendered and the check verdict is correct.