fix(bench): anchor hero display to showcase pick, fix gitref links

[spetz]

Hero headline read hardware from stale context and name from
the sweep's peak-throughput benchmark, so displayed fields
often didn't match the tail chart or "View details" target.

Route all hero headline fields through a single
showcase_display helper sourced from the same pick that
drives the chart and detail link. Gitref URL now prefixes
server- only for parseable semver tags; raw commits link
unmodified (iggy releases tag as server-X.Y.Z, commits do
not).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 19.35%. Comparing base (832c341) to head (49918aa).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@              Coverage Diff              @@
##             master    #3147       +/-   ##
=============================================
- Coverage     73.25%   19.35%   -53.91%     
  Complexity      943      943               
=============================================
  Files          1126     1124        -2     
  Lines         98435    87640    -10795     
  Branches      75609    64814    -10795     
=============================================
- Hits          72108    16962    -55146     
- Misses        23720    70286    +46566     
+ Partials       2607      392     -2215     

Components	Coverage Δ
Rust Core	0.35% <ø> (-73.78%)	⬇️
Java SDK	62.30% <ø> (ø)
C# SDK	69.40% <ø> (ø)
Python SDK	81.43% <ø> (ø)
Node SDK	91.44% <ø> (ø)
Go SDK	39.41% <ø> (ø)
see 623 files with indirect coverage changes

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