fix(orphan): handle prefixes with dots in orphan detection (GH#508)

The orphan detection was incorrectly flagging issues with dots in their
prefix (e.g., "my.project-abc123") as orphans because it was looking for
any dot in the ID, treating everything before the first dot as the
parent ID.

The fix:
- Add IsHierarchicalID() helper that correctly detects hierarchical IDs
  by checking if the ID ends with .{digits} (e.g., "bd-abc.1")
- Update SQL query in orphan detection migration to use GLOB patterns
  that only match IDs ending with numeric suffixes
- Update all Go code that checks for hierarchical IDs to use the new
  helper function

Test cases added:
- Unit tests for IsHierarchicalID covering normal, dotted prefix, and
  edge cases
- Integration test verifying dotted prefixes do not trigger false
  positives

Fixes: #508

internal/storage/sqlite/ids_test.go

@@ -0,0 +1,134 @@
+package sqlite
+
+import "testing"
+
+// TestIsHierarchicalID tests the IsHierarchicalID function which detects
+// if an issue ID is hierarchical (has a parent) based on the .N suffix pattern.
+// This test covers the fix for GH#508 where prefixes with dots were incorrectly
+// flagged as hierarchical.
+func TestIsHierarchicalID(t *testing.T) {
+	tests := []struct {
+		name             string
+		id               string
+		wantHierarchical bool
+		wantParentID     string
+	}{
+		// Standard hierarchical IDs
+		{
+			name:             "simple child .1",
+			id:               "bd-abc123.1",
+			wantHierarchical: true,
+			wantParentID:     "bd-abc123",
+		},
+		{
+			name:             "child .2",
+			id:               "bd-xyz789.2",
+			wantHierarchical: true,
+			wantParentID:     "bd-xyz789",
+		},
+		{
+			name:             "multi-digit child .10",
+			id:               "bd-test.10",
+			wantHierarchical: true,
+			wantParentID:     "bd-test",
+		},
+		{
+			name:             "large child number .999",
+			id:               "bd-issue.999",
+			wantHierarchical: true,
+			wantParentID:     "bd-issue",
+		},
+		{
+			name:             "nested hierarchical",
+			id:               "bd-parent.1.2",
+			wantHierarchical: true,
+			wantParentID:     "bd-parent.1",
+		},
+
+		// Non-hierarchical IDs (no suffix or non-numeric suffix)
+		{
+			name:             "simple top-level",
+			id:               "bd-abc123",
+			wantHierarchical: false,
+			wantParentID:     "",
+		},
+		{
+			name:             "no dot at all",
+			id:               "test-issue",
+			wantHierarchical: false,
+			wantParentID:     "",
+		},
+
+		// GH#508: Prefixes with dots should NOT be detected as hierarchical
+		{
+			name:             "prefix with dot - my.project",
+			id:               "my.project-abc123",
+			wantHierarchical: false,
+			wantParentID:     "",
+		},
+		{
+			name:             "prefix with multiple dots",
+			id:               "com.example.app-issue1",
+			wantHierarchical: false,
+			wantParentID:     "",
+		},
+		{
+			name:             "prefix with dot AND hierarchical child",
+			id:               "my.project-abc123.1",
+			wantHierarchical: true,
+			wantParentID:     "my.project-abc123",
+		},
+		{
+			name:             "complex prefix with hierarchical",
+			id:               "com.example.app-xyz.5",
+			wantHierarchical: true,
+			wantParentID:     "com.example.app-xyz",
+		},
+
+		// Edge cases
+		{
+			name:             "dot but non-numeric suffix",
+			id:               "bd-abc.def",
+			wantHierarchical: false,
+			wantParentID:     "",
+		},
+		{
+			name:             "mixed suffix (starts with digit)",
+			id:               "bd-test.1abc",
+			wantHierarchical: false,
+			wantParentID:     "",
+		},
+		{
+			name:             "trailing dot only",
+			id:               "bd-test.",
+			wantHierarchical: false,
+			wantParentID:     "",
+		},
+		{
+			name:             "empty after dot",
+			id:               "bd-test.",
+			wantHierarchical: false,
+			wantParentID:     "",
+		},
+		{
+			name:             "child 0",
+			id:               "bd-parent.0",
+			wantHierarchical: true,
+			wantParentID:     "bd-parent",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			gotHierarchical, gotParentID := IsHierarchicalID(tt.id)
+			if gotHierarchical != tt.wantHierarchical {
+				t.Errorf("IsHierarchicalID(%q) hierarchical = %v, want %v",
+					tt.id, gotHierarchical, tt.wantHierarchical)
+			}
+			if gotParentID != tt.wantParentID {
+				t.Errorf("IsHierarchicalID(%q) parentID = %q, want %q",
+					tt.id, gotParentID, tt.wantParentID)
+			}
+		})
+	}
+}