fix(context): complete RepoContext migration for remaining sync files (#1114)

Follow-up to #1102 - migrates remaining git command locations to use
RepoContext API for correct repo resolution when BEADS_DIR is set.

Files migrated:
- sync_branch.go: getCurrentBranch, showSyncStatus, mergeSyncBranch
- sync_check.go: checkForcedPush
- sync_import.go: doSyncFromMain
- autoimport.go: readFromGitRef, checkGitForIssues
- status.go: getGitActivity
- import.go: attemptAutoMerge (gitRoot lookup)
- reinit_test.go: add ResetCaches for test isolation

Pattern used throughout:
- Try RepoContext first: rc.GitCmd() runs in beads repo
- Fallback to CWD for tests or repos without beads
- Graceful degradation maintains backwards compatibility

cmd/bd/import.go

@@ -14,6 +14,7 @@ import (
 	"time"
 
 	"github.com/spf13/cobra"
+	"github.com/steveyegge/beads/internal/beads"
 	"github.com/steveyegge/beads/internal/debug"
 	"github.com/steveyegge/beads/internal/storage/sqlite"
 	"github.com/steveyegge/beads/internal/types"
@@ -635,20 +636,27 @@ func countLinesInGitHEAD(filePath string, workDir string) int {
 	return lines
 }
 
-// attemptAutoMerge attempts to resolve git conflicts using bd merge 3-way merge
+// attemptAutoMerge attempts to resolve git conflicts using bd merge 3-way merge.
+// GH#1110: Now uses RepoContext to ensure we operate on the beads repo.
 func attemptAutoMerge(conflictedPath string) error {
 	// Validate inputs
 	if conflictedPath == "" {
 		return fmt.Errorf("no file path provided for merge")
 	}
 
-	// Get git repository root
-	gitRootCmd := exec.Command("git", "rev-parse", "--show-toplevel") // #nosec G204 -- fixed git invocation for repo root discovery
-	gitRootOutput, err := gitRootCmd.Output()
-	if err != nil {
-		return fmt.Errorf("not in a git repository: %w", err)
+	// Get git repository root from RepoContext
+	var gitRoot string
+	if rc, err := beads.GetRepoContext(); err == nil {
+		gitRoot = rc.RepoRoot
+	} else {
+		// Fallback to CWD-based lookup
+		gitRootCmd := exec.Command("git", "rev-parse", "--show-toplevel") // #nosec G204 -- fixed git invocation for repo root discovery
+		gitRootOutput, err := gitRootCmd.Output()
+		if err != nil {
+			return fmt.Errorf("not in a git repository: %w", err)
+		}
+		gitRoot = strings.TrimSpace(string(gitRootOutput))
 	}
-	gitRoot := strings.TrimSpace(string(gitRootOutput))
 
 	// Convert conflicted path to absolute path relative to git root
 	absConflictedPath := conflictedPath