Improve mobile-first dashboard and viewer layouts

.agents/evidence/pr/mobile-first-ui/README.md

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+Mobile-first UI evidence captured from a real Claude Code trace.
+
+Source trace data:
+
+- Temporary capture database: `/tmp/ct-mobile-evidence/traces.sqlite3`
+- Session id: `86f7471f-4089-42a2-ac03-0f58a75de45f`
+- Session model: `claude-sonnet-4-6`
+- Session prompt: `Reply exactly: mobile-layout-real-trace-ok`
+- API records: 2
+
+Trace capture:
+
+```bash
+CLOUDTAP_DB=/tmp/ct-mobile-evidence/traces.sqlite3 \
+  timeout 45s uv run python -m claude_tap \
+  --tap-no-live \
+  --tap-no-open \
+  --tap-no-update-check \
+  --tap-output-dir /tmp/ct-mobile-evidence/out \
+  -- -p --tools '' --no-session-persistence --max-budget-usd 0.03 \
+  'Reply exactly: mobile-layout-real-trace-ok'
+```
+
+Local dashboard server:
+
+```bash
+CLOUDTAP_DB=/tmp/ct-mobile-evidence/traces.sqlite3 \
+  uv run claude-tap dashboard \
+  --tap-output-dir /tmp/ct-mobile-evidence/out \
+  --tap-live-port 33117 \
+  --tap-no-open
+```
+
+Screenshots:
+
+- `dashboard-mobile-list-320.png`: dashboard session cards at 320px.
+- `dashboard-mobile-actions-320.png`: dashboard mobile card action row at 320px.
+- `dashboard-mobile-list-375.png`: dashboard session cards at 375px.
+- `dashboard-tablet-list-768.png`: tablet-width dashboard session cards at 768px.
+- `dashboard-desktop-table-1440.png`: desktop dashboard table at 1440px.
+- `viewer-mobile-list-320.png`: standalone viewer list state at 320px.
+- `viewer-mobile-list-375.png`: standalone viewer list state at 375px.
+- `viewer-mobile-detail-320.png`: standalone viewer detail state at 320px.
+- `viewer-mobile-detail-375.png`: standalone viewer detail state at 375px.
+- `viewer-desktop-detail-1440.png`: standalone viewer detail state at 1440px.
+
+Capture assertions:
+
+- `/api/sessions` returned exactly the generated session.
+- Every captured viewport reported page-level `overflowX <= 2`.
+- Dashboard mobile refresh control renders as an icon with `aria-label="Refresh"`, not a literal `R`.
+- Viewer mobile detail action buttons stay inside the action bar, including `Diff with Prev`.
+- Viewer detail evidence keeps long `System Prompt` and `Messages` sections collapsed to avoid exposing local paths or private prompt context in public PR screenshots.
+
+Manual screenshot review:
+
+- No mobile screenshot shows clipped primary actions.
+- No screenshot shows synthetic or mock trace data.
+- No screenshot exposes secrets, tokens, local email addresses, or expanded long prompt context.