Fix MString::read() infinite retry loop, HTTPRequest parser fd leak, Log deadlock, log rotation symlink handling, and JString bounds checks

- MString::read() now gives up after repeated I/O errors instead of
  looping forever and crashing via realloc() failure (root cause of a
  recurring barant.com production crash).
- HTTPRequest::parse() no longer leaks lineParser/headerParser on a
  malformed request.
- Log gained size-based rotation (config-driven) and a non-static-mutex
  fix; a separate fix stopped rotation from destroying the logs symlink
  on its first trigger.
- File.cpp: symlink-preserving rotation support.
- JString: fixed an array-index out-of-bounds and a setString issue.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

File.h

@@ -29,11 +29,34 @@ namespace coreutils {
       size_t size;
       bool eof();
 
+      ///
+      /// Real, on-disk size of this file right now, queried directly
+      /// from the OS via fstat() - not the "size" member above, which
+      /// is only ever set at open()/read() time and goes stale the
+      /// moment anything else appends to this fd (exactly the case for
+      /// a long-lived, append-mode file such as Log's static logFile).
+      ///
+
+      size_t currentSize();
+
+      ///
+      /// Close this file, shift any existing ".1" .. ".maxBackups-1"
+      /// backups up by one (deleting whatever already sits at
+      /// ".maxBackups"), rename the current file to ".1", then reopen
+      /// a fresh file at the original path/mode/authority. Meant for a
+      /// long-lived, append-mode file that needs a size cap - not
+      /// meaningful for a file opened for reading.
+      ///
+
+      void rotate(int maxBackups);
+
       coreutils::ZString fileName;
 
     private:
       void open(coreutils::ZString fileName, int mode, int authority);
       int fd;
+      int mode;
+      int authority;
       coreutils::ZString zstring;
       bool mEof = false;