DXL2-C 1.0.0

First public release.

Added

• DYNAMIXEL Protocol 2.0 codec: CRC-16 (polynomial 0x8005), byte stuffing
  and unstuffing, incremental byte-stream parser that resynchronizes on the
  next header, encoder with output-capacity checks.
• Transport-independent link (dxl2_link_*): bytes in, packets out, through a
  user write callback and packet handler; valid and invalid packet counters.
• All instruction and status error values of the ROBOTIS specification, and
  little-endian helpers (dxl2_get_u16/u32, dxl2_put_u16/u32).
• Build-time configuration DXL2_MAX_PACKET_SIZE (default 256 bytes), checked
  at compile time.
• Examples: bare metal (UART interrupt, ring buffer, main loop; runs in CI on a
  simulated board), host serial port PING tool (Linux, macOS, Windows), Zephyr
  application.
• DXL2 Studio GUI (tools/dxl2_gui) for simulation and serial-port debugging.
• Documentation website (MkDocs Material): introduction, getting started,
  architecture, usage, extension guide, wire format with diagrams, integration
  guide, examples, DXL2 Studio, API reference (hand-written and Doxygen),
  configuration with measured stack usage, MISRA C:2012 compliance, author and
  license pages.
• Printable A4 PDF user manual with cover, table of contents and page numbers
  (tools/docs/build_manual.py), published with the website and every release.

Quality

• MISRA C:2012: 0 violations reported by the Cppcheck addon; three advisory
  deviations recorded in docs/misra.md. CI fails on any violation.
• Unit tests (GoogleTest): 100 % line and branch coverage of src/, enforced
  in CI.
• Integration tests (pytest): Python codec and a C/Python cross-check on
  random packets; ROBOTIS reference packets as regression vectors.
• Cppcheck and CodeQL static analysis in CI.