Lower browser PKCE mint priority; HTTP-first by default.

Browser path is slow; only use it as fallback after HTTP mint fails unless
cpa_prefer_browser_mint is explicitly enabled.

config.json

@@ -40,6 +40,9 @@
     "cpa_push_required": false,
     "cpa_prefer_sso_oauth": true,
     "cpa_require_referrer": true,
+    "cpa_prefer_browser_mint": false,
+    "cpa_allow_browser_fallback": true,
+    "cpa_browser_mint_timeout_sec": 90,
     "cpa_allow_device_fallback": false,
     "mint_proxy": "",
     "mint_timeout_sec": 300,