feat: add git file status and enhanced git widgets

[tejasdc]

Summary

Adds 7 new git widgets addressing issue #20 ("Add enhanced git status options to git widgets"). These provide granular git repository status information that the current widget set lacks — file-level counts, upstream tracking, conflict detection, clean/dirty status, and commit SHA.

All widgets follow existing patterns exactly: Widget interface, git-no-git shared helpers, hideNoGit metadata support, rawValue mode, and cross-platform git commands via runGit().

Comparable in scope to PR #201 (Skills widget) — 19 files changed, 1,378 lines added.

New Widgets

Widget	Type String	Default Output	rawValue	Color	Git Command
Git Staged Files	git-staged-files	S:3	3	green	git diff --cached --name-only
Git Unstaged Files	git-unstaged-files	M:2	2	yellow	git diff --name-only
Git Untracked Files	git-untracked-files	A:1	1	red	git ls-files --others --exclude-standard
Git Ahead/Behind	git-ahead-behind	↑2 ↓1	2 1	cyan	git rev-list --left-right --count HEAD...@{upstream}
Git Merge Conflicts	git-merge-conflicts	⚠1	1	red	git diff --name-only --diff-filter=U
Git Clean Status	git-clean-status	✓ / ✗	clean / dirty	green	git status --porcelain
Git SHA	git-sha	a3f2c1d	N/A	brightBlack	git rev-parse --short HEAD

Edge Cases

• No upstream branch: git-ahead-behind shows (no upstream) or hides via hideNoGit
• No merge conflicts: git-merge-conflicts returns null (hidden) — only visible when conflicts exist
• Clean working tree: File count widgets show S:0, M:0, A:0 — counts are always meaningful
• Detached HEAD: git-sha works normally; git-ahead-behind falls back to no-upstream behavior

Complementary to PR #153

PR #153 (git-indicators) adds binary yes/no indicators for staged/unstaged. These widgets provide actual counts and cover additional features (untracked files, ahead/behind, conflicts, clean status, SHA). The two are complementary, not overlapping.

Changes

File	Change
src/widgets/GitStagedFiles.ts	New widget: staged file count
src/widgets/GitUnstagedFiles.ts	New widget: unstaged file count
src/widgets/GitUntrackedFiles.ts	New widget: untracked file count
src/widgets/GitAheadBehind.ts	New widget: ahead/behind upstream
src/widgets/GitMergeConflicts.ts	New widget: merge conflict count
src/widgets/GitCleanStatus.ts	New widget: clean/dirty indicator
src/widgets/GitSha.ts	New widget: short commit SHA
src/widgets/__tests__/GitStagedFiles.test.ts	Tests for staged files widget
src/widgets/__tests__/GitUnstagedFiles.test.ts	Tests for unstaged files widget
src/widgets/__tests__/GitUntrackedFiles.test.ts	Tests for untracked files widget
src/widgets/__tests__/GitAheadBehind.test.ts	Tests for ahead/behind widget
src/widgets/__tests__/GitMergeConflicts.test.ts	Tests for merge conflicts widget
src/widgets/__tests__/GitCleanStatus.test.ts	Tests for clean status widget
src/widgets/__tests__/GitSha.test.ts	Tests for SHA widget
src/utils/git.ts	Add getGitFileStatusCounts() utility + GitFileStatusCounts interface
src/utils/__tests__/git.test.ts	Tests for new git utility
src/widgets/index.ts	Add 7 new widget exports
src/utils/widget-manifest.ts	Add 7 new manifest entries
src/widgets/__tests__/GitWidgetSharedBehavior.test.ts	Add 7 entries to shared behavior tests

14 new files + 5 modified files = 19 files total

Implementation Details

Shared Utility: getGitFileStatusCounts()

Added to src/utils/git.ts — returns { staged, unstaged, untracked } counts. Used by the three file count widgets to avoid redundant git command logic.

export interface GitFileStatusCounts {
    staged: number;
    unstaged: number;
    untracked: number;
}

Pattern Compliance

Every widget follows the exact patterns established by existing git widgets:

• Implements Widget interface from src/types/Widget.ts
• Uses git-no-git shared helpers for hideNoGit toggle and keybinds
• Uses isInsideGitWorkTree() to gate git operations
• Uses runGit() for all git commands (cross-platform via child_process.execSync)
• Supports rawValue mode where applicable
• Returns null to hide when appropriate (no git, no upstream, no conflicts)
• Includes preview values for the TUI editor

Test Plan

• 21 new tests across 7 test files — all passing
• Each widget tested for: preview mode, normal rendering, rawValue mode, no-git fallback, hideNoGit behavior, error handling
• GitAheadBehind additionally tested for: no-upstream (empty output), no-upstream (throw), invalid output parsing
• GitMergeConflicts tested for: zero conflicts returning null (hidden)
• Shared behavior tests updated with 7 new entries
• getGitFileStatusCounts() utility tested
• bun run lint passes (TypeScript type checking + ESLint)
• Tested locally with live Claude Code status line

Closes #20