feat(gate): add bd gate check for GitHub gate evaluation (bd-oos3)

Implement Phase 3 of gate evaluation: GitHub gates (gh:run and gh:pr).

## Changes

- Add `bd gate check` command to evaluate open gates
- Support --type=gh to check all GitHub gates
- Support --type=gh:run for GitHub Actions workflow run gates
- Support --type=gh:pr for pull request merge status gates
- Add --dry-run flag to preview gate resolution without closing
- Auto-close gates when conditions are met:
  - gh:run: workflow completed with success
  - gh:pr: PR merged
- Escalate when conditions fail:
  - gh:run: workflow failed or cancelled
  - gh:pr: PR closed without merging
- Add unit tests for shouldCheckGate filtering

Note: mol-refinery-patrol.formula.toml updated in gastown rig to include
check-github-gates step (version 4).

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

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

cmd/bd/gate_test.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/steveyegge/beads/internal/types"
+)
+
+func TestShouldCheckGate(t *testing.T) {
+	tests := []struct {
+		name       string
+		awaitType  string
+		typeFilter string
+		want       bool
+	}{
+		// Empty filter matches all
+		{"empty filter matches gh:run", "gh:run", "", true},
+		{"empty filter matches gh:pr", "gh:pr", "", true},
+		{"empty filter matches timer", "timer", "", true},
+		{"empty filter matches human", "human", "", true},
+
+		// "all" filter matches all
+		{"all filter matches gh:run", "gh:run", "all", true},
+		{"all filter matches gh:pr", "gh:pr", "all", true},
+		{"all filter matches timer", "timer", "all", true},
+
+		// "gh" filter matches all GitHub types
+		{"gh filter matches gh:run", "gh:run", "gh", true},
+		{"gh filter matches gh:pr", "gh:pr", "gh", true},
+		{"gh filter does not match timer", "timer", "gh", false},
+		{"gh filter does not match human", "human", "gh", false},
+
+		// Exact type filters
+		{"gh:run filter matches gh:run", "gh:run", "gh:run", true},
+		{"gh:run filter does not match gh:pr", "gh:pr", "gh:run", false},
+		{"gh:pr filter matches gh:pr", "gh:pr", "gh:pr", true},
+		{"gh:pr filter does not match gh:run", "gh:run", "gh:pr", false},
+		{"timer filter matches timer", "timer", "timer", true},
+		{"timer filter does not match gh:run", "gh:run", "timer", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			gate := &types.Issue{
+				AwaitType: tt.awaitType,
+			}
+			got := shouldCheckGate(gate, tt.typeFilter)
+			if got != tt.want {
+				t.Errorf("shouldCheckGate(%q, %q) = %v, want %v",
+					tt.awaitType, tt.typeFilter, got, tt.want)
+			}
+		})
+	}
+}