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

tests/integration/test_api.py

@@ -70,6 +70,38 @@ def test_styles_and_js_served(client) -> None:
     assert client.get("/assets/app.js").status_code == 200
 
 
+# Emoji code points banned from UI chrome (phase 08): the pictograph
+# blocks, VS-16/ZWJ, plus the exact glyphs the old light theme used
+# (🧠 🧑 👋 📂 ⚠).
+_EMOJI_GLYPHS = "\U0001F9E0\U0001F9D1\U0001F44B\U0001F4C2\u26A0"
+
+
+def _find_emoji(text: str) -> list[str]:
+    hits: list[str] = []
+    for ch in text:
+        cp = ord(ch)
+        if (
+            0x1F300 <= cp <= 0x1FAFF
+            or 0x2600 <= cp <= 0x27BF
+            or 0x2B00 <= cp <= 0x2BFF
+            or cp in (0xFE0F, 0x200D)
+            or ch in _EMOJI_GLYPHS
+        ):
+            hits.append(ch)
+    return hits
+
+
+@pytest.mark.parametrize(
+    "path", ["/", "/sources.html", "/assets/app.js", "/assets/styles.css"]
+)
+def test_ui_chrome_has_no_emoji(client, path: str) -> None:
+    """Permanent regression guard (phase 08): the UI chrome — both pages,
+    the JS that renders it, and the stylesheet — is emoji-free."""
+    r = client.get(path)
+    assert r.status_code == 200
+    assert _find_emoji(r.text) == [], f"emoji found in {path}: {_find_emoji(r.text)!r}"
+
+
 def test_chat_requires_message(client) -> None:
     r = client.post("/api/chat", json={"message": ""})
     assert r.status_code == 422