Compare resolved canonical Path values, not raw string spellings, when
detecting a question_path / proposal_path collision. A relative
proposal_path and an absolute question_path that name the same file now
fail closed with reason "path_collision" instead of resolving.
Adds a regression test for the absolute-vs-relative same-file collision
and keeps the existing exact-string collision test. The new test is
non-vacuous: it fails under the prior raw-string comparison.
Scope: ask_handle.py seam + its test only. No runtime.py, CLAIMS,
metrics, telemetry, schema, or lane-pin changes.
c0d6493219