feat: merge heartbeat service improvements from feat-heartbeat branch

- Add ChannelSender interface for sending heartbeat results to users
- Add sendResponse() to automatically deliver results to last channel
- Add createDefaultHeartbeatTemplate() for first-run setup
- Support HEARTBEAT_OK silent response (legacy compatibility)
- Add structured logging with INFO/ERROR levels
- Move integration tests to separate file with build tag

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

pkg/providers/claude_cli_provider_integration_test.go

@@ -0,0 +1,126 @@
+//go:build integration
+
+package providers
+
+import (
+	"context"
+	exec "os/exec"
+	"strings"
+	"testing"
+	"time"
+)
+
+// TestIntegration_RealClaudeCLI tests the ClaudeCliProvider with a real claude CLI.
+// Run with: go test -tags=integration ./pkg/providers/...
+func TestIntegration_RealClaudeCLI(t *testing.T) {
+	// Check if claude CLI is available
+	path, err := exec.LookPath("claude")
+	if err != nil {
+		t.Skip("claude CLI not found in PATH, skipping integration test")
+	}
+	t.Logf("Using claude CLI at: %s", path)
+
+	p := NewClaudeCliProvider(t.TempDir())
+
+	ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
+	defer cancel()
+
+	resp, err := p.Chat(ctx, []Message{
+		{Role: "user", Content: "Respond with only the word 'pong'. Nothing else."},
+	}, nil, "", nil)
+
+	if err != nil {
+		t.Fatalf("Chat() with real CLI error = %v", err)
+	}
+
+	// Verify response structure
+	if resp.Content == "" {
+		t.Error("Content is empty")
+	}
+	if resp.FinishReason != "stop" {
+		t.Errorf("FinishReason = %q, want %q", resp.FinishReason, "stop")
+	}
+	if resp.Usage == nil {
+		t.Error("Usage should not be nil from real CLI")
+	} else {
+		if resp.Usage.PromptTokens == 0 {
+			t.Error("PromptTokens should be > 0")
+		}
+		if resp.Usage.CompletionTokens == 0 {
+			t.Error("CompletionTokens should be > 0")
+		}
+		t.Logf("Usage: prompt=%d, completion=%d, total=%d",
+			resp.Usage.PromptTokens, resp.Usage.CompletionTokens, resp.Usage.TotalTokens)
+	}
+
+	t.Logf("Response content: %q", resp.Content)
+
+	// Loose check - should contain "pong" somewhere (model might capitalize or add punctuation)
+	if !strings.Contains(strings.ToLower(resp.Content), "pong") {
+		t.Errorf("Content = %q, expected to contain 'pong'", resp.Content)
+	}
+}
+
+func TestIntegration_RealClaudeCLI_WithSystemPrompt(t *testing.T) {
+	if _, err := exec.LookPath("claude"); err != nil {
+		t.Skip("claude CLI not found in PATH")
+	}
+
+	p := NewClaudeCliProvider(t.TempDir())
+
+	ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
+	defer cancel()
+
+	resp, err := p.Chat(ctx, []Message{
+		{Role: "system", Content: "You are a calculator. Only respond with numbers. No text."},
+		{Role: "user", Content: "What is 2+2?"},
+	}, nil, "", nil)
+
+	if err != nil {
+		t.Fatalf("Chat() error = %v", err)
+	}
+
+	t.Logf("Response: %q", resp.Content)
+
+	if !strings.Contains(resp.Content, "4") {
+		t.Errorf("Content = %q, expected to contain '4'", resp.Content)
+	}
+}
+
+func TestIntegration_RealClaudeCLI_ParsesRealJSON(t *testing.T) {
+	if _, err := exec.LookPath("claude"); err != nil {
+		t.Skip("claude CLI not found in PATH")
+	}
+
+	// Run claude directly and verify our parser handles real output
+	cmd := exec.Command("claude", "-p", "--output-format", "json",
+		"--dangerously-skip-permissions", "--no-chrome", "--no-session-persistence", "-")
+	cmd.Stdin = strings.NewReader("Say hi")
+	cmd.Dir = t.TempDir()
+
+	output, err := cmd.Output()
+	if err != nil {
+		t.Fatalf("claude CLI failed: %v", err)
+	}
+
+	t.Logf("Raw CLI output: %s", string(output))
+
+	// Verify our parser can handle real output
+	p := NewClaudeCliProvider("")
+	resp, err := p.parseClaudeCliResponse(string(output))
+	if err != nil {
+		t.Fatalf("parseClaudeCliResponse() failed on real CLI output: %v", err)
+	}
+
+	if resp.Content == "" {
+		t.Error("parsed Content is empty")
+	}
+	if resp.FinishReason != "stop" {
+		t.Errorf("FinishReason = %q, want stop", resp.FinishReason)
+	}
+	if resp.Usage == nil {
+		t.Error("Usage should not be nil")
+	}
+
+	t.Logf("Parsed: content=%q, finish=%s, usage=%+v", resp.Content, resp.FinishReason, resp.Usage)
+}