feat(backend): replace Selenium with Playwright

BREAKING CHANGE: backend now requires Python 3.12 or newer.

tests/test_backend_browser_automation.py

@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+from backend.workers.browser_automation import (
+    PlaywrightLaunchConfig,
+    extract_cookie_value,
+    extract_payload_header,
+)
+
+
+def test_payload_header_extraction_is_case_insensitive() -> None:
+    headers = {
+        "Accept": "application/json",
+        "X-API-Request-Payload": "live-signature",
+    }
+
+    assert extract_payload_header(headers) == "live-signature"
+
+
+def test_payload_header_extraction_ignores_blank_values() -> None:
+    headers = {"x-api-request-payload": "   "}
+
+    assert extract_payload_header(headers) is None
+
+
+def test_cookie_value_extraction_finds_named_cookie() -> None:
+    cookies = [
+        {"name": "other", "value": "unused"},
+        {"name": "token", "value": "qq-token"},
+    ]
+
+    assert extract_cookie_value(cookies, "token") == "qq-token"
+
+
+def test_launch_config_uses_optional_executable_path() -> None:
+    config = PlaywrightLaunchConfig(executable_path="/usr/bin/chromium")
+
+    assert config.to_launch_kwargs()["executable_path"] == "/usr/bin/chromium"