feat(chat): retry the last answer — redo-in-place Retry button on the latest brain bubble

frontend/assets/styles.css

@@ -623,6 +623,35 @@ details.thinking .thinking-text ul { margin: 0 0 0.5rem; }
 .tune-btn svg { width: 14px; height: 14px; display: block; }
 .tune-btn:hover { background: var(--brand-soft); color: var(--brand-ink); }
 
+/* Phase 49 (owner-locked 2026-08-29, TODO.md L4): the "Retry" button —
+   the redo-in-place action in the meta row of the LAST brain bubble.
+   The exact visual family of .tune-btn (same pill size/spacing, the
+   global :focus-visible ring, >=44px via min-height) so the two meta
+   actions read as a pair — but neutral: ink-soft -> ink on hover (Tune
+   keeps the brand pair). The redo glyph rides currentColor. Contrast:
+   ink-soft on --bg ~8.6:1, ink ~15:1, hover ink on --brand-soft
+   ~15.7:1 — all AA. */
+.retry-btn {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  gap: 0.35rem;
+  min-height: 44px;
+  margin-left: auto;
+  padding: 0.35rem 0.8rem;
+  border-radius: 999px;
+  border: 1px solid var(--line);
+  background: transparent;
+  color: var(--ink-soft);
+  font: inherit;
+  font-weight: 600;
+  font-size: 0.82rem;
+  white-space: nowrap;
+  cursor: pointer;
+}
+.retry-btn svg { width: 14px; height: 14px; display: block; }
+.retry-btn:hover { background: var(--brand-soft); color: var(--ink); }
+
 /* Phase 48: the "Stopped" note in a stopped brain bubble's meta row:
    ink-soft on the surface bubble ≈6.9:1, the 10px filled-square glyph
    centered with the row (the Tune button shares the row), and
@@ -2322,6 +2351,7 @@ details.thinking .thinking-text ul { margin: 0 0 0.5rem; }
   .steering-note { padding: 0.3rem 0.3rem 0.3rem 0.7rem; }
   .app-main > .steering-panel { width: calc(100% - 1.8rem); }
   .tune-btn { min-height: 44px; }
+  .retry-btn { min-height: 44px; }
   /* Phase 27: the tuning page squeezes like the other cards — the row
      padding tightens; the icon+label actions keep their 44px floor and
      the note text ellipsizes (min-width: 0). */