Generate a summary of today's commits authored by the authenticated GitHub user.

The tool:

1. Detects the authenticated GitHub user from the token.

2. Fetches every repository where the user is an owner, collaborator, or organisation member.

3. Retrieves all commits pushed since the start of today (UTC).

4. Filters to commits authored by the authenticated user.

5. Groups commits by repository.

6. Returns a formatted, human-readable summary.

Returns: A dict with a single key "summary" containing the formatted text.

Example return value::

{
    "summary": "> Evorgs\n\n* Simplified layout structure ...\n\n> BMS\n\n* Work in payment feature."
}

Return all repositories accessible by the authenticated GitHub user.

Includes repositories where the user is an owner, collaborator, or organisation member.

Returns: A dict with key "repositories" containing a list of objects, each with full_name, name, owner, private, and default_branch fields.

Example return value::

{
    "repositories": [
        {
            "full_name": "octocat/Hello-World",
            "name": "Hello-World",
            "owner": "octocat",
            "private": false,
            "default_branch": "main"
        }
    ]
}

Return today's commits for a single repository authored by the authenticated user.

Args: repo_name: The repository to inspect. Accepts either the short name (e.g. "Hello-World") or the full owner/repo format (e.g. "octocat/Hello-World"). When a short name is provided the authenticated user's login is used as the owner.

Returns: A dict with keys:

* ``"repo"``    – the resolved ``owner/repo`` string
* ``"commits"`` – list of commit objects
* ``"summary"`` – formatted bullet-list summary for this repository

Example return value::

{
    "repo": "octocat/Hello-World",
    "commits": [
        {
            "sha": "abc123",
            "message": "Fix login bug",
            "files": ["auth/login.py"],
            "insertions": 5,
            "deletions": 2,
            "committed_at": "2024-01-15T09:30:00+00:00"
        }
    ],
    "summary": "> Hello-World\n\n* Fix login bug"
}