feat: foundations — canonical types, Parse grammar, env DSNs, health, chains

Phase 1 of the majordomo build:
- llm/ canonical contract (messages, parts, tools, capabilities, streaming,
  Model/Provider, error classification)
- health/ clock-injected tracker (threshold bench, exponential capped
  cooldown, reset-on-success)
- root Registry + Parse (verbatim model ids, inline recursive alias
  expansion with cycle detection, chain dedup), LLM_* env-DSN providers
  (go-llm parity: lazy fallback + eager LoadEnv), health-aware chain
  executor behind the Model interface
- provider/fake scriptable test provider; hermetic test suite incl. the
  trailing-thinking chain and foreman:// env loading
- ADRs 0001-0008, CLAUDE.md, README (honest matrix), CI workflow,
  docs/phase-1-design.md

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

llm/message_test.go

@@ -0,0 +1,62 @@
+package llm
+
+import "testing"
+
+func TestMessageText(t *testing.T) {
+	m := UserParts(Text("a "), Image("image/png", []byte{1}), Text("b"))
+	if got := m.Text(); got != "a b" {
+		t.Errorf("Text = %q, want %q", got, "a b")
+	}
+}
+
+func TestConstructors(t *testing.T) {
+	if m := SystemText("s"); m.Role != RoleSystem || m.Text() != "s" {
+		t.Errorf("SystemText = %+v", m)
+	}
+	if m := UserText("u"); m.Role != RoleUser || m.Text() != "u" {
+		t.Errorf("UserText = %+v", m)
+	}
+	if m := AssistantText("a"); m.Role != RoleAssistant || m.Text() != "a" {
+		t.Errorf("AssistantText = %+v", m)
+	}
+	m := ToolResultsMessage(ToolResult{ID: "1", Content: "ok"})
+	if m.Role != RoleTool || len(m.ToolResults) != 1 {
+		t.Errorf("ToolResultsMessage = %+v", m)
+	}
+}
+
+func TestResponseTextAndMessage(t *testing.T) {
+	r := &Response{
+		Parts:     []Part{Text("hello "), Text("world")},
+		ToolCalls: []ToolCall{{ID: "1", Name: "t"}},
+	}
+	if got := r.Text(); got != "hello world" {
+		t.Errorf("Text = %q", got)
+	}
+	m := r.Message()
+	if m.Role != RoleAssistant || m.Text() != "hello world" || len(m.ToolCalls) != 1 {
+		t.Errorf("Message = %+v", m)
+	}
+}
+
+func TestUsageAccumulation(t *testing.T) {
+	u := Usage{InputTokens: 10, OutputTokens: 5}
+	u.Add(Usage{InputTokens: 1, OutputTokens: 2})
+	if u.InputTokens != 11 || u.OutputTokens != 7 || u.Total() != 18 {
+		t.Errorf("usage = %+v", u)
+	}
+}
+
+func TestCapabilitiesHelpers(t *testing.T) {
+	c := Capabilities{}
+	if c.SupportsImages() {
+		t.Error("zero MaxImagesPerReq must mean images unsupported")
+	}
+	if !c.MIMEAllowed("image/png") {
+		t.Error("empty AllowedImageMIME must allow any type")
+	}
+	c = Capabilities{MaxImagesPerReq: 2, AllowedImageMIME: []string{"image/jpeg"}}
+	if !c.SupportsImages() || c.MIMEAllowed("image/png") || !c.MIMEAllowed("image/jpeg") {
+		t.Errorf("capabilities helpers misbehave: %+v", c)
+	}
+}