refactor: consolidate duplicate path-finding utilities (bd-74w1, bd-4nqq)

- Add git.GetRepoRoot() with Windows path normalization
- Update beads.findGitRoot() to delegate to git.GetRepoRoot()
- Replace findBeadsDir() with beads.FindBeadsDir() across 8 files
- Remove duplicate findBeadsDir() and findGitRoot() function definitions
- Remove dead test code (TestInfoCommand, TestInfoWithNoDaemon)
- Update tests to work with consolidated APIs

Part of Code Health Review Dec 2025 epic (bd-tggf).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/info_test.go

@@ -5,14 +5,6 @@ import (
 	"testing"
 )
 
-func TestInfoCommand(t *testing.T) {
-	t.Skip("Manual test - bd info command is working, see manual testing")
-}
-
-func TestInfoWithNoDaemon(t *testing.T) {
-	t.Skip("Manual test - bd info --no-daemon command is working, see manual testing")
-}
-
 func TestVersionChangesStructure(t *testing.T) {
 	// Verify versionChanges is properly structured
 	if len(versionChanges) == 0 {