feat: add category-specific hints to provider form

- Add dynamic hint text based on provider category (official, opensource, aggregator, third-party, custom)
- Display hints in ProviderPresetSelector below preset buttons
- Rename "Chinese official" to "Opensource official" for better clarity
- Add i18n keys for all category hints in both zh and en locales
- Remove redundant hint boxes from ClaudeFormFields and CodexFormFields

This improves user guidance by showing contextual hints that explain
what fields are required for each provider category.

src/i18n/locales/en.json

@@ -211,6 +211,11 @@
     "codexApiKeyAutoFill": "Just fill in here, auth.json below will be auto-filled",
     "kimiApiKeyHint": "Fill in to get model list",
     "apiKeyAutoFill": "Just fill in here, config below will be auto-filled",
+    "cnOfficialApiKeyHint": "💡 Opensource official providers only need API Key, endpoint is preset",
+    "aggregatorApiKeyHint": "💡 Aggregator providers only need API Key to use",
+    "thirdPartyApiKeyHint": "💡 Third-party providers require both API Key and endpoint",
+    "customApiKeyHint": "💡 Custom configuration requires manually filling all necessary fields",
+    "officialHint": "💡 Official provider uses browser login, no API Key needed",
     "getApiKey": "Get API Key",
     "parameterConfig": "Parameter Config - {{name}} *",
     "mainModel": "Main Model (optional)",
@@ -236,7 +241,7 @@
     "smallModelPlaceholder": "claude-3-5-haiku-20241022",
     "modelHelper": "Optional: Specify default Claude model to use, leave blank to use system default.",
     "categoryOfficial": "Official",
-    "categoryCnOfficial": "China Official",
+    "categoryCnOfficial": "Opensource Official",
     "categoryAggregation": "Aggregation",
     "categoryThirdParty": "Third Party"
   },