test(coverage): add unit tests across all packages; remove dead code

- Added comprehensive table-driven test suites for all packages:
  cmd/glint, cicontext, fetcher, graph, linter, model, resolver.
  Coverage reaches 98%+ statement coverage across the codebase.
- Replaced os.Exit calls in cmd/glint with an `exit` variable so tests
  can capture exit codes without terminating the test process.
- Removed unreachable code found during coverage analysis:
  dead guard in cicontext.parseRegexLiteral; dead len(jobs)==0 branch
  in graph.Pipeline; skipWin struct field and dead continue in
  graph.convertToPNG; pipelineSVG return type simplified to string.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/graph/tree_test.go

@@ -0,0 +1,154 @@
+package graph
+
+import (
+	"strings"
+	"testing"
+
+	"git.k3nny.fr/glint/internal/cicontext"
+	"git.k3nny.fr/glint/internal/model"
+)
+
+func makeSimplePipeline() *model.Pipeline {
+	return &model.Pipeline{
+		Stages: []string{"build", "test"},
+		Jobs: map[string]model.Job{
+			"build-job": {Name: "build-job", Stage: "build"},
+			"test-job":  {Name: "test-job", Stage: "test"},
+			".template": {Name: ".template", Stage: "build"},
+		},
+	}
+}
+
+func TestTree_Basic(t *testing.T) {
+	p := makeSimplePipeline()
+	out := Tree(p, nil)
+	if !strings.Contains(out, "pipeline") {
+		t.Error("expected 'pipeline' root node")
+	}
+	if !strings.Contains(out, "build-job") {
+		t.Error("expected build-job in tree")
+	}
+	if !strings.Contains(out, "test-job") {
+		t.Error("expected test-job in tree")
+	}
+	// hidden template jobs should not appear
+	if strings.Contains(out, ".template") {
+		t.Error(".template job should be excluded from tree")
+	}
+}
+
+func TestTree_WithContext_Skipped(t *testing.T) {
+	p := &model.Pipeline{
+		Stages: []string{"build"},
+		Jobs: map[string]model.Job{
+			"run-on-tag": {Name: "run-on-tag", Stage: "build", Rules: []model.Rule{
+				{If: `$CI_COMMIT_TAG != ""`, When: "on_success"},
+			}},
+		},
+	}
+	ctx := cicontext.New("main", "", "", nil)
+	out := Tree(p, ctx)
+	if !strings.Contains(out, "[skipped]") {
+		t.Errorf("expected [skipped] annotation, got:\n%s", out)
+	}
+}
+
+func TestTree_WithContext_Manual(t *testing.T) {
+	p := &model.Pipeline{
+		Stages: []string{"deploy"},
+		Jobs: map[string]model.Job{
+			"deploy": {Name: "deploy", Stage: "deploy", When: "manual"},
+		},
+	}
+	ctx := cicontext.New("main", "", "", nil)
+	out := Tree(p, ctx)
+	if !strings.Contains(out, "[manual]") {
+		t.Errorf("expected [manual] annotation, got:\n%s", out)
+	}
+}
+
+func TestTree_NoContext_Annotations(t *testing.T) {
+	p := &model.Pipeline{
+		Stages: []string{"build"},
+		Jobs: map[string]model.Job{
+			"manual-job":  {Name: "manual-job", Stage: "build", When: "manual"},
+			"delayed-job": {Name: "delayed-job", Stage: "build", When: "delayed"},
+			"trigger-job": {Name: "trigger-job", Stage: "build", Trigger: "other/project"},
+		},
+	}
+	out := Tree(p, nil)
+	if !strings.Contains(out, "[manual]") { t.Error("expected [manual]") }
+	if !strings.Contains(out, "[delayed]") { t.Error("expected [delayed]") }
+	if !strings.Contains(out, "[trigger]") { t.Error("expected [trigger]") }
+}
+
+func TestTree_JobWithNoStage(t *testing.T) {
+	// Jobs without a stage should default to "test"
+	p := &model.Pipeline{
+		Stages: []string{"test"},
+		Jobs: map[string]model.Job{
+			"nostage": {Name: "nostage"},
+		},
+	}
+	out := Tree(p, nil)
+	if !strings.Contains(out, "test") { t.Error("expected default stage 'test'") }
+}
+
+func TestTree_UndeclaredStage(t *testing.T) {
+	// Job in a stage not listed in p.Stages — should still appear
+	p := &model.Pipeline{
+		Stages: []string{},
+		Jobs: map[string]model.Job{
+			"myjob": {Name: "myjob", Stage: "custom"},
+		},
+	}
+	out := Tree(p, nil)
+	if !strings.Contains(out, "myjob") { t.Error("expected myjob in output") }
+}
+
+// ── branchChars ───────────────────────────────────────────────────────────────
+
+func TestBranchChars(t *testing.T) {
+	b, c := branchChars(true)
+	if b != "└── " || c != "    " {
+		t.Errorf("last: branch=%q cont=%q", b, c)
+	}
+	b, c = branchChars(false)
+	if b != "├── " || c != "│   " {
+		t.Errorf("not-last: branch=%q cont=%q", b, c)
+	}
+}
+
+// ── jobLabel ─────────────────────────────────────────────────────────────────
+
+func TestJobLabel(t *testing.T) {
+	job := model.Job{Name: "j"}
+	if jobLabel(job, "j", nil) != "j" {
+		t.Error("plain job should have plain label")
+	}
+
+	// Multiple tags
+	job2 := model.Job{Name: "j2", When: "manual", Trigger: "other"}
+	label := jobLabel(job2, "j2", nil)
+	if !strings.Contains(label, "manual") || !strings.Contains(label, "trigger") {
+		t.Errorf("expected manual+trigger in label: %q", label)
+	}
+
+	// With context — active job has no annotation
+	emptyCtx := &cicontext.Context{}
+	if jobLabel(model.Job{}, "j", emptyCtx) != "j" {
+		t.Error("active job with context should have no annotation")
+	}
+}
+
+// TestJobLabel_ActiveWithContext covers the 'return name' path when a job runs
+// normally (neither skipped nor manual) with a non-empty context.
+func TestJobLabel_ActiveWithContext(t *testing.T) {
+	// Branch context with a job that has no rules → the job is active.
+	ctx := cicontext.New("main", "", "", nil)
+	activeJob := model.Job{Name: "build", Script: []any{"make"}}
+	label := jobLabel(activeJob, "build", ctx)
+	if label != "build" {
+		t.Errorf("active job with context: expected 'build', got %q", label)
+	}
+}