feat: c5

[daniel-cohere]

This PR introduces Command 5 (CMD5) support to the Melody parsing and templating library. CMD5 is a new prompt format that uses XML-like, cofl-tagged tool calls instead of the JSON action blocks in CMD4.

• Parsing:

  • Adds a new FilterCoflAction struct and associated methods to parse cofl-tagged tool calls.
  • The parse_cofl_actions method handles incremental parsing of cofl tool call streams.
  • Supports both raw and processed parameter streaming modes.
  • Includes extensive tests for the cofl parser covering various tool call scenarios.

• Templating:

  • Adds a new render_cmd5 function that uses the CMD5 jinja template.
  • The RenderCmd5Options type is an alias for RenderCmd4Options since CMD5 reuses the same option schema.
  • Template selection logic prioritizes template_id, then template_jinja, and falls back to the default CMD5 template.
  • Includes tests for the CMD5 renderer with various template configurations.

• Python Bindings:

  • Adds render_cmd5 to the Python module.
  • Includes tests for the Python CMD5 renderer.

• Other Changes:

  • Updates the special token map to include CMD5 tokens.
  • Adds CMD5-specific template files and updates the template configuration.
  • Updates documentation and comments to reflect CMD5 support.

Overall, this PR adds comprehensive support for the new CMD5 format while maintaining compatibility with existing CMD3 and CMD4 functionality. The changes are well-tested and follow the existing architecture of the library.

---

Note

Medium Risk
New streaming tool-call parsing path and format presets affect inference/templating correctness, but behavior is heavily fixture- and unit-tested and cmd3/cmd4 paths are explicitly isolated.

Overview
Introduces Command 5 (CMD5): same prompt options as CMD4, but tool calls use cofl XML (<cofl:tool_calls> / <cofl:tool_param>) instead of JSON <|START_ACTION|> blocks. A new incremental cofl_filter parser drives FilterOptions::cmd5() (with isolation so cmd3/cmd4 JSON actions do not leak into cmd5 and vice versa), plus render_cmd5 and bundled cmd5.jinja (XML-escaped params, shared cmd4 platform/reasoning pieces).

Bindings: Python (PyFilter.cmd5, render_cmd5, stubs), Go (RenderCMD5, Cmd5 / HandleMultiHopCmd5), and FFI (melody_render_cmd5, melody_filter_options_cmd5). cmd4-v1 Jinja now honors reasoning / reasoning_content in thinking macros (aligned with cmd4-v2/cmd5).

Infra: crate version 0.10.0; Python CI installs the local sdist so tests do not pick up a stale PyPI wheel; ty config allows optional vllm / cohere_melody imports; FFI option conversion preserves non-empty template_jinja even when use_jinja is false (needed for cmd5 custom templates).

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