feat(chat): remove legacy bubble renderer, full-bleed is the only chat style (#881)

Deletes the ChatMessageList/ChatStreaming bubble path and the ChatStyle
setting (issue #866 phase 6). ChatScreen now renders FullBleedChatList
directly; ChatBubble becomes the user-message anchor with the shared
SystemBubble/InlineAttachment/formatTimestamp helpers intact. Stubs of
AuthManager.getChatStyle() removed from four test suites; TodoTaskCardTest
renders ToolBubble directly.

Verified: ktlintCheck green, testDebugUnitTest 962/962 pass, assembleDebug
APK builds.

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

app/src/main/java/com/m57/hermescontrol/data/config/ServerStoreState.kt

@@ -1,7 +1,6 @@
 package com.m57.hermescontrol.data.config
 
 import com.m57.hermescontrol.data.model.PinnedModel
-import com.m57.hermescontrol.theme.ChatStyle
 import com.m57.hermescontrol.theme.ThemePreference
 import com.m57.hermescontrol.theme.ThemePreset
 import kotlinx.serialization.Serializable
@@ -22,9 +21,6 @@ data class ServerStoreState(
     val wsAuthParam: String = "token",
     val typingEffectEnabled: Boolean = true,
     val typingEffectDelayMs: Int = 30,
-    // Chat rendering style (issue #866): full-bleed renderer (default) or the
-    // legacy bubble renderer.
-    val chatStyle: ChatStyle = ChatStyle.FULL_BLEED,
     // App display language. "system" = follow device locale; otherwise a BCP-47
     // language code such as "en" or "ko". Applied via ContextWrapper in MainActivity.
     val appLanguage: String = "system",

app/src/main/java/com/m57/hermescontrol/data/local/AuthManager.kt

@@ -17,7 +17,6 @@ import com.m57.hermescontrol.data.remote.CleartextPolicy
 import com.m57.hermescontrol.data.remote.CookieManager
 import com.m57.hermescontrol.data.remote.ServerEndpoint
 import com.m57.hermescontrol.data.session.ActiveSessionHolder
-import com.m57.hermescontrol.theme.ChatStyle
 import com.m57.hermescontrol.theme.ThemePreference
 import com.m57.hermescontrol.theme.ThemePreset
 import kotlinx.coroutines.CoroutineScope
@@ -75,9 +74,6 @@ object AuthManager {
     private val _themePresetFlow = MutableStateFlow<ThemePreset>(ThemePreset.DEFAULT)
     val themePresetFlow: StateFlow<ThemePreset> = _themePresetFlow.asStateFlow()
 
-    private val _chatStyleFlow = MutableStateFlow<ChatStyle>(ChatStyle.FULL_BLEED)
-    val chatStyleFlow: StateFlow<ChatStyle> = _chatStyleFlow.asStateFlow()
-
     private val _tokenFlow = MutableStateFlow<String?>(null)
     val tokenFlow: StateFlow<String?> = _tokenFlow.asStateFlow()
 
@@ -184,7 +180,6 @@ object AuthManager {
                     _themePreferenceFlow.value = state.themePreference
                     _useDynamicColorsFlow.value = state.useDynamicColors
                     _themePresetFlow.value = state.themePreset
-                    _chatStyleFlow.value = state.chatStyle
                     // B7 (Jul 08 2026, kanban t_470): keep cookie scope aligned with active profile.
                     appScope?.launch { syncCookieStoreForProfile(state.selectedProfileId) }
                 }
@@ -589,15 +584,6 @@ object AuthManager {
 
     fun getThemePreset(): ThemePreset = serverStore.getLatestState().themePreset
 
-    // ── Chat style (issue #866) ──────────────────────────────────────────
-
-    fun getChatStyle(): ChatStyle = serverStore.getLatestState().chatStyle
-
-    fun setChatStyle(style: ChatStyle) {
-        _chatStyleFlow.value = style
-        serverStore.update { it.copy(chatStyle = style) }
-    }
-
     fun setThemePreset(preset: ThemePreset) {
         serverStore.update { it.copy(themePreset = preset) }
     }