feat: add privacy mode, thinking levels, PWA support, and i18n

- Add privacy mode to hide IP and user preferences from AI requests
- Add model thinking levels (low/medium/high) for context analysis depth
- Add PWA support with service worker, manifest, and app icons
- Add SettingsPanel for user preferences (theme, background, language)
- Add i18n translations for en/zh/ja/ko/de/fr
- Add Pinia store for centralized settings management
- Update backend to support user preferences and thinking levels
- Update config to use absolute API URLs

backend/prompt.py

@@ -29,20 +29,46 @@ def prepare_prompt_context(prefix: str, suffix: str) -> Tuple[str, str]:
     return _prepare_context(prefix, suffix)
 
 
-def build_prompt(prefix: str, suffix: str, language_id: str = "markdown", location: str = "") -> str:
+def build_prompt(
+    prefix: str, 
+    suffix: str, 
+    language_id: str = "markdown", 
+    location: str = "",
+    thinking_level: str = "low",
+    preferences: object = None
+) -> str:
     safe_language_id = _sanitize_language_id(language_id)
     recent_prefix, recent_suffix = _prepare_context(prefix, suffix)
     current_time = _get_current_datetime()
     location_info = f"\nUser location: {location}" if location else ""
+    
+    thinking_instruction = ""
+    if thinking_level == "medium":
+        thinking_instruction = "\n- Briefly analyze the context before suggesting."
+    elif thinking_level == "high":
+        thinking_instruction = "\n- Deeply analyze the context, structure, and intent before suggesting. Think step-by-step."
 
-    prompt = f"""Current time: {current_time}{location_info}
+    pref_info = []
+    if preferences:
+        if preferences.language and preferences.language != 'auto':
+            pref_info.append(f"Preferred language: {preferences.language}")
+        if preferences.currency and preferences.currency != 'auto':
+            pref_info.append(f"Preferred currency: {preferences.currency}")
+        if preferences.timezone and preferences.timezone != 'auto':
+            pref_info.append(f"User timezone: {preferences.timezone}")
+    
+    preferences_instruction = "\n".join(pref_info)
+    if preferences_instruction:
+        preferences_instruction = f"\nUser Preferences:\n{preferences_instruction}"
+
+    prompt = f"""Current time: {current_time}{location_info}{preferences_instruction}
 
 You are an inline completion engine for a {safe_language_id} editor with ghost-text suggestions.
 
 Your job:
 - Return ONLY the text that should be inserted at the cursor between PREFIX and SUFFIX.
 - Prefer a meaningful, non-empty insertion with moderate length.
-- Avoid overly short outputs with little information value.
+- Avoid overly short outputs with little information value.{thinking_instruction}
 
 Important context:
 - PREFIX may contain OCR metadata inline after images, e.g. ![alt](url) <OCR:description>.