fix(#284): remove dead code across API, models, WS client, and docs (#299)

Remove six dead-code findings from the automated review:
- CODE-01: updateProfileDescription endpoint + UpdateProfileDescriptionRequest DTO (uncalled)
- CODE-02: getConfig() endpoint (app uses getRawConfig())
- CODE-03: TogglePluginRequest DTO (unreferenced)
- CODE-05: mark isConnected with @VisibleForTesting (test-only usage)
- CODE-06: fix KDoc createdAt -> timestamp to match actual field name

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

app/src/main/java/com/m57/hermescontrol/data/remote/HermesApiService.kt

@@ -37,7 +37,6 @@ import com.m57.hermescontrol.data.model.SystemStatsResponse
 import com.m57.hermescontrol.data.model.ToggleSkillRequest
 import com.m57.hermescontrol.data.model.Toolset
 import com.m57.hermescontrol.data.model.ToolsetToggleRequest
-import com.m57.hermescontrol.data.model.UpdateProfileDescriptionRequest
 import com.m57.hermescontrol.data.model.UpdateProfileModelRequest
 import com.m57.hermescontrol.data.model.UpdateProfileSoulRequest
 import com.m57.hermescontrol.data.model.UpdateRawConfigRequest
@@ -78,9 +77,6 @@ interface HermesApiService {
     @GET("api/system/stats")
     suspend fun getSystemStats(): Response<SystemStatsResponse>
 
-    @GET("api/config")
-    suspend fun getConfig(): Response<Map<String, Any?>>
-
     @GET("api/skills")
     suspend fun getSkills(): Response<List<Skill>>
 
@@ -149,12 +145,6 @@ interface HermesApiService {
         @Body body: UpdateProfileModelRequest,
     ): Response<Unit>
 
-    @PUT("api/profiles/{name}/description")
-    suspend fun updateProfileDescription(
-        @Path("name") name: String,
-        @Body body: UpdateProfileDescriptionRequest,
-    ): Response<Unit>
-
     @GET("api/tools/toolsets")
     suspend fun getToolsets(): Response<List<Toolset>>