feat(ui): dark tech theme — emoji-free chrome, subtle animated CSS background, WCAG AA dark palette

tests/e2e/test_honest_deflection.py

@@ -101,7 +101,7 @@ def test_off_topic_question_deflects_honestly(
 
     # Visually distinct from a normal answer (accent-bg / accent-line).
     style = bubble.evaluate("el => getComputedStyle(el)")
-    assert style["backgroundColor"] == "rgb(255, 247, 232)"  # --accent-bg #fff7e8
+    assert style["backgroundColor"] == "rgb(43, 33, 16)"  # --accent-bg #2b2110 (dark theme)
     assert style["borderTopColor"] == "rgb(245, 158, 11)"  # --accent-line #f59e0b
 
     # ≥2 "Maybe try:" chips below the bubble, in an accessible group.
@@ -114,8 +114,8 @@ def test_off_topic_question_deflects_honestly(
     expect(group.first).to_have_attribute("role", "list")
     # Chip component contract: brand pill, ≥44px touch target.
     chip_style = chips.first.evaluate("el => getComputedStyle(el)")
-    assert chip_style["backgroundColor"] == "rgb(238, 240, 254)"  # --brand-soft
-    assert chip_style["color"] == "rgb(55, 48, 163)"  # --brand-ink
+    assert chip_style["backgroundColor"] == "rgb(35, 43, 82)"  # --brand-soft #232b52 (dark theme)
+    assert chip_style["color"] == "rgb(165, 180, 252)"  # --brand-ink #a5b4fc
     box = chips.first.bounding_box()
     assert box is not None and box["height"] >= 44