Add git_operations and github_operations modules from mcp_coder

[MarcusJellinghaus]

Goal

Land mcp_coder's utils/git_operations/ (13 files) and utils/github_operations/ (~15 files) into mcp_workspace as MCP tools. After this issue, mcp_workspace exposes git and GitHub functionality that mcp_coder can consume via MCP.

Why

Per the mcp_utils_plan Phase 5 and architectural rule #2 (one server per domain): git state is workspace state, and GitHub API mechanics belong with the server that already handles file/git ops.

Scope — what moves

Git operations → expand existing file_tools/git_operations.py (currently 134 lines, 3 functions):

• core.py, branches.py, branch_queries.py, commits.py, diffs.py, compact_diffs.py, file_tracking.py, staging.py, remotes.py, parent_branch_detection.py, repository_status.py, workflows.py, __init__.py

GitHub operations → new file_tools/github_operations.py module:

• base_manager.py, github_utils.py, pr_manager.py, labels_manager.py, label_config.py, ci_results_manager.py, issues/ subpackage (all 9 files)

Refactoring rules

Per mcp_coder/.claude/knowledge_base/refactoring_principles.md:

• Move, don't change. Functions/classes land as-is. No logic changes.
• Only adjust imports. Internal cross-references update to new paths, nothing else.
• Tests mirror source structure. Unit tests from mcp_coder move with the code.
• File size check. All new files must be under 750 lines. Split if needed.

Acceptance criteria

• All git_operations functions exist in mcp_workspace and are exposed as MCP tools
• All github_operations functions exist in mcp_workspace and are exposed as MCP tools
• Unit tests moved and passing (pytest -n auto)
• pylint, mypy, ruff pass
• mcp-coder check file-size --max-lines 750 passes
• No logic changes — only import adjustments (verify with mcp-coder git-tool compact-diff)
• CLAUDE.md updated if needed

Related

• Tracked from mcp_coder: consume git/github ops from mcp_workspace, delete local copies mcp_coder#813 (consumer-side shim + deletion)