Traceability: vendor the shared gate, annotate the source

Adds jray-project as a submodule at scripts/vendor/jray-project, so this repo
runs the same extractor as every other component rather than its own copy, and
gains the system spec that defines the PR/SR requirements its register traces
up to.

scripts/traceability-gate.sh is a thin wrapper holding only what is specific to
this repo: UR/DR prefixes, .rs sources, and REPO_ROOT — which the shared gate
cannot infer once vendored, since its default resolves to the submodule itself.
Each override fails silently in a way that looks like "no work done" rather
than "misconfigured", so the wrapper documents why each is needed.

Annotates 35 units with TRACES tags, on the code that decides rather than every
helper it calls. Coverage is 23/32 (71.9%) with no orphan tags. The nine
untraced are genuinely unimplemented: UR-007 is plugin-side, UR-008 is
federation, and UR-015..018 are the pending SR-003 schema bump.

The gate caught a real error in the first pass: several tags separated IDs of
different types with commas. A comma joins IDs within one type; a pipe
separates types. Fixed, and the diagnostics are now clean.

MIN_COVERAGE stays 0 deliberately. The gate still fails on orphan tags, a >100%
ratio, a register parsing to nothing, or an empty source scan — raise the
threshold as a ratchet once the remaining work lands.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/castcheck.rs

@@ -79,6 +79,7 @@ fn name_key(s: &str) -> String {
 ///
 /// `credits` is the reference set *C*: for a movie, its credits; for an episode,
 /// the union of per-episode credits and the series' aggregate credits.
+/// TRACES: UR-003, UR-005, UR-010 | SR-001, SR-004
 pub fn evaluate(submitted: &[SubmittedActor], credits: &[CastMember]) -> CastCheckOutcome {
     let m = submitted.len();
 
@@ -211,6 +212,7 @@ fn classify(m: usize, matches: usize, ratio: f64) -> Verdict {
 ///
 /// Rejects when a matched person is flagged adult by TMDB and the target title
 /// is not, which targets the stated prank without needing a blocklist of names.
+/// TRACES: UR-005 | SR-004
 pub fn category_guard_violation(matched: &[MatchedActor], title_is_adult: bool) -> Option<u64> {
     if title_is_adult {
         return None;