Refactor: Remove IDE SharedPreferences access, enforce plugin isolation

Removed getAppSharedPreferences() from PluginContext to enforce proper
data isolation. Plugins should only manage their own preferences via
getPluginSharedPreferences(), not access IDE internal settings.

Benefits:
- Enforces plugin data isolation
- Prevents unintended coupling with IDE preferences
- Reduces IDE API surface for plugins
- Plugins have dedicated storage for their settings

Addresses code review feedback from Daniel-ADFA:
'I think plugins should be able to manage their own sharepref,
they don't need to access the IDEs'

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Author: jatezzz

plugin-api/src/main/kotlin/com/itsaky/androidide/plugins/PluginContext.kt

@@ -40,18 +40,9 @@ interface PluginContext {
      */
     fun getPluginFilesDir(): File
 
-    /**
-     * Get SharedPreferences from the main application for reading migration data
-     * Used to read settings from built-in Agent preferences
-     *
-     * @param prefsName Name of the preferences file (e.g., "AgentPrefs")
-     * @return SharedPreferences instance or null if not found
-     */
-    fun getAppSharedPreferences(prefsName: String): android.content.SharedPreferences?
-
     /**
      * Get SharedPreferences for the plugin for writing migrated data
-     * Used to write settings to plugin storage during migration
+     * Plugins should only manage their own preferences for data isolation
      *
      * @param prefsName Name of the preferences file (e.g., "AgentSettings")
      * @return SharedPreferences instance

plugin-manager/src/main/kotlin/com/itsaky/androidide/plugins/manager/context/PluginContextImpl.kt

@@ -34,15 +34,6 @@ class PluginContextImpl(
         return File(androidContext.filesDir, "plugins/$pluginId").apply { mkdirs() }
     }
 
-    override fun getAppSharedPreferences(prefsName: String): SharedPreferences? {
-        return try {
-            androidContext.getSharedPreferences(prefsName, Context.MODE_PRIVATE)
-        } catch (e: Exception) {
-            logger.error("Failed to access app SharedPreferences: $prefsName", e)
-            null
-        }
-    }
-
     override fun getPluginSharedPreferences(prefsName: String): SharedPreferences {
         return androidContext.getSharedPreferences("plugin_${pluginId}_${prefsName}", Context.MODE_PRIVATE)
     }