provide ability for agents to create structured commits using git-com config.

Nobody has claimed this yet.

Because of the interactive nature of the TUI (minimal as it is) people who are using agentic systems to create commits can't use git-com.

# User Story
As a user of agentic platforms
I want my agents to be able to create commits that adhere to the `.git-com.yaml` in the repo
So that we can leverage the benefits of having structured commits in our git log.

# Proposal
## Git-Com changes
enable git-com to read from a structured file (YAML?) that contains all the content that would be provided by each input in the config.

### Notes
- Should validate that all fields are all present (not just required fields) because if it skips optional fields we can't know that if that was a mistake or intentional.
- Should allow `null` for optional items.
- Should have a flag that would make it delete (or not delete?) the temp file after a successful commit.
- what would the structure look like for telling it you want to add an option to a list vs just providing an option that already exits in a list? Is that different syntax, or do we just assume something not in the list should be added?

## Agent Stuff
Create a skill (with an associated tool?) that teaches / enables an agent to read the `.git-com.yaml` and know what options are available and what to do when "Other" is an option.

I think maybe a cli tool creates instructions for the agent to follow for constructing the YAML file that then gets passed to git-com.

As well as checking that `git-com` is installed, and available in the `PATH`

### Questions
Should agents be able to make new items in (multi-)select lists? I think that should be a new meta thing in the `.git-com.yaml` if not present it would be assumed that the agent should not create a new item, and should instead ask the user which of the provided options to use.

The issue names .git-com.yaml and the git-com CLI but no implementation files or tests. Start by locating how the CLI reads configuration and builds commits, then define the structured input and validation behavior, including optional nulls, list values, and temporary-file handling. Done means agents can provide validated structured data and create commits that follow the repository configuration.

Written by the indexing model from the issue text.