Fix: Client log dialog stops updating past edit-control default limit

The Win32 EDIT control caps text at ~32K/64K chars by default, so the
client log dialog silently stopped accepting appends long before the
512KB truncation logic could run. Call SetLimitText(0) in both
CClientLog and CActivityDialog to lift the cap.

Also unify newline handling in Logger: each entry now ends with exactly
one '\n' at the source, so the in-memory ring-buffer dump (used by the
TCP log query) splits into lines correctly instead of relying on every
Mprintf caller ending its format with '\n'. writeToFile drops the extra
std::endl accordingly.

Additionally fix a CFont leak in CClientLog::OnInitDialog by moving the
font to a member.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

common/logger.h

@@ -152,6 +152,12 @@ public:
                                id + "[" + timestamp + "] [" + file + ":" + std::to_string(line) + "] " + message:
                                id + "[" + timestamp + "] "  + message;
 
+        // 方案B：在源头统一保证每条日志以单个 '\n' 结尾，文件与内存 ring buffer
+        // 共用同一份文本；写文件时不再额外追加换行，内存导出直接拼接即可正确分行。
+        while (!logEntry.empty() && (logEntry.back() == '\n' || logEntry.back() == '\r'))
+            logEntry.pop_back();
+        logEntry += '\n';
+
         // Always record to in-memory ring buffer regardless of enable flag.
         {
             std::lock_guard<std::mutex> lock(m_memMutex);
@@ -305,7 +311,7 @@ private:
         std::lock_guard<std::mutex> lock(fileMutex);
         std::ofstream logFile(logFileName, std::ios::app);
         if (logFile.is_open()) {
-            logFile << logEntry << std::endl;
+            logFile << logEntry;  // logEntry 已在 log() 中以单个 '\n' 结尾
         }
     }