Auto-detect git remote name instead of assuming 'origin'

[seefood]

Summary

Adds automatic detection of git remote name when BASH_IT_REMOTE is not set, fixing issues for users with non-standard remote names like me, upstream, fork, etc.

Problem

Commands like bash-it version, bash-it update, and bash-it doctor hard-coded the remote name as "origin", causing failures when users have different remote naming conventions:

$ bash-it version
error: No such remote 'origin'

Solution

Created _bash-it-get-remote-name() helper function that:

1. Returns BASH_IT_REMOTE if already set (preserves user override)
2. Auto-detects first available remote via git remote | head -n 1
3. Falls back to "origin" if no remotes found

Updated three functions to use auto-detection:

• _bash-it-update-() (lib/helpers.bash:254)
• _bash-it-version() (lib/helpers.bash:370)
• _bash-it-doctor-summary() (lib/helpers.bash:564)

Benefits

• ✅ No configuration required for single-remote repos
• ✅ Works with any remote name (me, fork, upstream, etc.)
• ✅ Backward compatible: BASH_IT_REMOTE override still works
• ✅ Fallback to "origin" maintains existing behavior for edge cases

Testing

• Verified with non-standard remote name 'me'
• Tested BASH_IT_REMOTE environment variable preservation
• Shellcheck passes with no warnings
• All pre-commit hooks pass

Fixes #2317

🤖 Generated with Claude Code

[seefood]

Closing as duplicate of #2344. Both PRs solve the same issue (#2317 - auto-detect git remote name). PR #2344 was created first and already has review feedback, so that should be the one to merge.