Stop reading a coverage calculation as a diagnostics subsystem

NFR-OPS-1 asks for structured levelled logging to a rotating, size-capped
on-disk log in the XDG state or Android app directory, automatic redaction of
credentials and tokens, and a one-click diagnostics bundle with an explicit
preview-and-consent step. Its two tags were on `compute_coverage` and on the
traceability tool's gesture extractor.

Neither is diagnostics under any reading. One computes a ratio and the other
generates a markdown document; neither writes a log, and no rotating on-disk
log exists anywhere in the tree — logging goes to stderr and to logcat.

These were real tags, not the fixtures the extractor was just taught to
ignore, which makes them the more instructive case: the tool was correct and
the tags were wrong. NFR-OPS-1 is untagged again, and outstanding.md §9 now
says what is actually missing rather than that the requirement is covered.

`gestures.rs` keeps its FR-UI-4 tag, which is a separate claim and unaffected.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tools/traceability/src/lib.rs

@@ -306,7 +306,6 @@ fn trim_body(line: &str) -> String {
 ///
 /// This signature is the fix for the 158% bug: `defined` is required, so there
 /// is nowhere for a frozen denominator to hide.
-/// TRACES: NFR-OPS-1
 pub fn compute_coverage(traced: &BTreeSet<String>, defined: &DefinedRequirements) -> Coverage {
     let traced_reqs: BTreeSet<&String> = traced.iter().filter(|id| is_requirement(id)).collect();