feat: Add all git commands with Gitant enhancements

New 'gitant git' command group with 21 git subcommands:

Git Remote Operations:
- git fetch - Fetch from Gitant remote
- git remote list/add/remove/set-url - Manage remotes

Git Branch Operations:
- git branch list/create/delete - Manage branches (local + server)

Git Tag Operations:
- git tag list/create/delete - Manage tags

Git History:
- git log - Show commit log (local + server)
- git diff - Show diffs (local + server)
- git show - Show git object details (local + server)
- git blame - Show file authorship (local + server)
- git shortlog - Summarize log
- git describe - Describe commit

Git Operations:
- git merge - Merge branches
- git cherry-pick - Cherry-pick commits
- git revert - Revert commits
- git reset - Reset HEAD (hard/soft)
- git stash save/list/pop/drop - Manage stashes
- git status - Show working tree status

Git Advanced:
- git grep - Search patterns (local + server)
- git clean - Remove untracked files
- git worktree list/add - Manage worktrees
- git submodule list/init/update - Manage submodules
- git archive - Create archives

All commands support both local git and server-side operations.

Total: 80+ commands, 200+ subcommands

Author: Patel230