fix(autoimport): prevent export to wrong JSONL file (bd-tqo)

Add FindJSONLInDir helper that correctly prefers issues.jsonl over other
.jsonl files. Previously, glob patterns could return deletions.jsonl or
merge artifacts (beads.base.jsonl, etc.) first alphabetically, causing
issue data to be written to the wrong file.

This fixes the root cause of deletions.jsonl corruption where full issue
objects were written instead of deletion records, leading to all issues
being purged during sync.

Changes:
- Add FindJSONLInDir() in internal/autoimport with proper file selection
- Update AutoImportIfNewer() to use FindJSONLInDir
- Update CheckStaleness() to use FindJSONLInDir
- Update triggerExport() in RPC server to use FindJSONLInDir
- Add comprehensive tests for FindJSONLInDir

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

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

internal/autoimport/autoimport_test.go

@@ -517,3 +517,79 @@ func TestStderrNotifier(t *testing.T) {
 		notify.Infof("test info")
 	})
 }
+
+// TestFindJSONLInDir tests that FindJSONLInDir correctly prefers issues.jsonl
+// and avoids deletions.jsonl and merge artifacts (bd-tqo fix)
+func TestFindJSONLInDir(t *testing.T) {
+	tests := []struct {
+		name     string
+		files    []string
+		expected string
+	}{
+		{
+			name:     "only issues.jsonl",
+			files:    []string{"issues.jsonl"},
+			expected: "issues.jsonl",
+		},
+		{
+			name:     "issues.jsonl and deletions.jsonl - prefers issues",
+			files:    []string{"deletions.jsonl", "issues.jsonl"},
+			expected: "issues.jsonl",
+		},
+		{
+			name:     "issues.jsonl with merge artifacts - prefers issues",
+			files:    []string{"beads.base.jsonl", "beads.left.jsonl", "beads.right.jsonl", "issues.jsonl"},
+			expected: "issues.jsonl",
+		},
+		{
+			name:     "beads.jsonl as legacy fallback",
+			files:    []string{"beads.jsonl"},
+			expected: "beads.jsonl",
+		},
+		{
+			name:     "issues.jsonl preferred over beads.jsonl",
+			files:    []string{"beads.jsonl", "issues.jsonl"},
+			expected: "issues.jsonl",
+		},
+		{
+			name:     "only deletions.jsonl - returns default issues.jsonl",
+			files:    []string{"deletions.jsonl"},
+			expected: "issues.jsonl",
+		},
+		{
+			name:     "only merge artifacts - returns default issues.jsonl",
+			files:    []string{"beads.base.jsonl", "beads.left.jsonl", "beads.right.jsonl"},
+			expected: "issues.jsonl",
+		},
+		{
+			name:     "no files - returns default issues.jsonl",
+			files:    []string{},
+			expected: "issues.jsonl",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tmpDir, err := os.MkdirTemp("", "bd-findjsonl-test-*")
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer os.RemoveAll(tmpDir)
+
+			// Create test files
+			for _, file := range tt.files {
+				path := filepath.Join(tmpDir, file)
+				if err := os.WriteFile(path, []byte("{}"), 0644); err != nil {
+					t.Fatal(err)
+				}
+			}
+
+			result := FindJSONLInDir(tmpDir)
+			got := filepath.Base(result)
+
+			if got != tt.expected {
+				t.Errorf("FindJSONLInDir() = %q, want %q", got, tt.expected)
+			}
+		})
+	}
+}