fix(traces): overlay per-hop SNR on path graph for TRACE packets (#1004) (#1622)

## Summary
Phase 2 of #979 — overlay per-hop relay SNR onto the Traces page path
graph for TRACE-type packets.

When the viewed packet is a firmware TRACE and `decoded.snrValues` is
non-empty, each hop edge in the existing path graph gets a small `<text
class="hop-snr">` label at its midpoint with the corresponding numeric
SNR value (Tufte: numeric overlay only — edge color encodes observer
attribution, thickness encodes count; per triage, do **not**
double-encode).

Non-TRACE packets render unchanged. Observer-level SNR in the timeline
is unaffected (different concept: observer receive SNR vs relay hop
SNR).

## TDD
- **Red commit:** `8d441aa51e4b38dec962c7a32d31e9f7080f2786` — adds 4
assertions in `test-traces.js` against the (not-yet-emitted) `<text
class="hop-snr">` element. CI run: see Actions on this PR.
- **Green commit:** implements the SNR-label emission in
`renderPathGraph` (`public/traces.js`).

## Test
`test-traces.js` asserts:
- TRACE + non-empty `snrValues` → `<text class="hop-snr">` labels render
with the numeric values
- non-TRACE → labels absent (regression gate for AC2)
- TRACE + empty `snrValues` → labels absent
- `decoded` omitted → labels absent (back-compat)

Fixes #1004

---------

Co-authored-by: corescope-bot <bot@corescope.local>
Co-authored-by: clawbot <bot@openclaw.local>

.github/workflows/deploy.yml

@@ -138,6 +138,7 @@ jobs:
           node test-issue-1619-feed-detail-card-draggable.js
           node test-xss-escape-sinks.js
           node test-preflight-xss-gate.js
+          node test-traces.js
 
       - name: 🛡️ Preflight XSS gate — actual --diff check (PR only)
         # The fixture self-test above (test-preflight-xss-gate.js) only