refactor(chat): decompose into modular architecture, add GM commands, fix protocol

- Extract ChatPanel monolith into 15+ focused modules under ui/chat/
  (ChatInput, ChatTabManager, ChatTabCompleter, ChatMarkupParser,
  ChatMarkupRenderer, ChatCommandRegistry, ChatBubbleManager,
  ChatSettings, MacroEvaluator, GameStateAdapter, InputModifierAdapter)
- Split 2700-line chat_panel_commands.cpp into 11 command modules
- Add GM command handling: 190-command data table, dot-prefix interception,
  tab-completion, /gmhelp with category filter
- Fix ChatType enum to match WoW wire protocol (SAY=0x01 not 0x00);
  values 0x00-0x1B shared across Vanilla/TBC/WotLK
- Fix BG_SYSTEM_* values from 82-84 (UB in bitmask shifts) to 0x24-0x26
- Fix infinite Enter key loop after teleport (disable TOGGLE_CHAT repeat,
  add 2-frame input cooldown)
- Add tests: chat_markup_parser, chat_tab_completer, gm_commands,
  macro_evaluator

Signed-off-by: Pavel Okhlopkov <pavel.okhlopkov@flant.com>

include/ui/chat/chat_tab_manager.hpp

@@ -0,0 +1,54 @@
+#pragma once
+
+#include "game/world_packets.hpp"
+#include <imgui.h>
+#include <cstdint>
+#include <deque>
+#include <string>
+#include <vector>
+
+namespace wowee {
+namespace ui {
+
+/**
+ * Chat tab definitions, unread tracking, type colors, and type names.
+ *
+ * Extracted from ChatPanel (Phase 1.3 of chat_panel_ref.md).
+ * Owns the tab configuration, unread badge counts, and message filtering.
+ */
+class ChatTabManager {
+public:
+    ChatTabManager();
+
+    // ---- Tab access ----
+    int getTabCount() const { return static_cast<int>(tabs_.size()); }
+    const std::string& getTabName(int idx) const { return tabs_[idx].name; }
+    uint64_t getTabTypeMask(int idx) const { return tabs_[idx].typeMask; }
+
+    // ---- Unread tracking ----
+    int getUnreadCount(int idx) const;
+    void clearUnread(int idx);
+    /** Scan new messages since last call and increment unread counters for non-active tabs. */
+    void updateUnread(const std::deque<game::MessageChatData>& history, int activeTab);
+
+    // ---- Message filtering ----
+    bool shouldShowMessage(const game::MessageChatData& msg, int tabIndex) const;
+
+    // ---- Chat type helpers (static, no state needed) ----
+    static const char* getChatTypeName(game::ChatType type);
+    static ImVec4 getChatTypeColor(game::ChatType type);
+
+private:
+    struct ChatTab {
+        std::string name;
+        uint64_t typeMask;
+    };
+    std::vector<ChatTab> tabs_;
+    std::vector<int> unread_;
+    size_t seenCount_ = 0;
+
+    void initTabs();
+};
+
+} // namespace ui
+} // namespace wowee