Add bd config command for external integration configuration

- Add GetAllConfig/DeleteConfig methods to storage interface
- Implement config set/get/list/unset subcommands with JSON support
- Add comprehensive tests for config operations
- Create CONFIG.md with full documentation and examples
- Update README.md with config section
- Support namespace conventions (jira.*, linear.*, github.*, custom.*)

Closes bd-60

Amp-Thread-ID: https://ampcode.com/threads/T-33db7481-de7c-475e-b562-6afb7fb4bc7a
Co-authored-by: Amp <amp@ampcode.com>

cmd/bd/config_test.go

@@ -0,0 +1,171 @@
+package main
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/steveyegge/beads/internal/storage/sqlite"
+)
+
+func TestConfigCommands(t *testing.T) {
+	ctx := context.Background()
+	store, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	// Test SetConfig
+	err := store.SetConfig(ctx, "test.key", "test-value")
+	if err != nil {
+		t.Fatalf("SetConfig failed: %v", err)
+	}
+
+	// Test GetConfig
+	value, err := store.GetConfig(ctx, "test.key")
+	if err != nil {
+		t.Fatalf("GetConfig failed: %v", err)
+	}
+	if value != "test-value" {
+		t.Errorf("Expected 'test-value', got '%s'", value)
+	}
+
+	// Test GetConfig for non-existent key
+	value, err = store.GetConfig(ctx, "nonexistent.key")
+	if err != nil {
+		t.Fatalf("GetConfig for nonexistent key failed: %v", err)
+	}
+	if value != "" {
+		t.Errorf("Expected empty string for nonexistent key, got '%s'", value)
+	}
+
+	// Test SetConfig update
+	err = store.SetConfig(ctx, "test.key", "updated-value")
+	if err != nil {
+		t.Fatalf("SetConfig update failed: %v", err)
+	}
+	value, err = store.GetConfig(ctx, "test.key")
+	if err != nil {
+		t.Fatalf("GetConfig after update failed: %v", err)
+	}
+	if value != "updated-value" {
+		t.Errorf("Expected 'updated-value', got '%s'", value)
+	}
+
+	// Test GetAllConfig
+	err = store.SetConfig(ctx, "jira.url", "https://example.atlassian.net")
+	if err != nil {
+		t.Fatalf("SetConfig for jira.url failed: %v", err)
+	}
+	err = store.SetConfig(ctx, "jira.project", "PROJ")
+	if err != nil {
+		t.Fatalf("SetConfig for jira.project failed: %v", err)
+	}
+
+	config, err := store.GetAllConfig(ctx)
+	if err != nil {
+		t.Fatalf("GetAllConfig failed: %v", err)
+	}
+
+	// Should have at least our test keys (may have default compaction config too)
+	if len(config) < 3 {
+		t.Errorf("Expected at least 3 config entries, got %d", len(config))
+	}
+
+	if config["test.key"] != "updated-value" {
+		t.Errorf("Expected 'updated-value' for test.key, got '%s'", config["test.key"])
+	}
+	if config["jira.url"] != "https://example.atlassian.net" {
+		t.Errorf("Expected jira.url in config, got '%s'", config["jira.url"])
+	}
+	if config["jira.project"] != "PROJ" {
+		t.Errorf("Expected jira.project in config, got '%s'", config["jira.project"])
+	}
+
+	// Test DeleteConfig
+	err = store.DeleteConfig(ctx, "test.key")
+	if err != nil {
+		t.Fatalf("DeleteConfig failed: %v", err)
+	}
+
+	value, err = store.GetConfig(ctx, "test.key")
+	if err != nil {
+		t.Fatalf("GetConfig after delete failed: %v", err)
+	}
+	if value != "" {
+		t.Errorf("Expected empty string after delete, got '%s'", value)
+	}
+
+	// Test DeleteConfig for non-existent key (should not error)
+	err = store.DeleteConfig(ctx, "nonexistent.key")
+	if err != nil {
+		t.Fatalf("DeleteConfig for nonexistent key failed: %v", err)
+	}
+}
+
+func TestConfigNamespaces(t *testing.T) {
+	ctx := context.Background()
+	store, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	// Test various namespace conventions
+	namespaces := map[string]string{
+		"jira.url":                    "https://example.atlassian.net",
+		"jira.project":                "PROJ",
+		"jira.status_map.todo":        "open",
+		"linear.team_id":              "team-123",
+		"github.org":                  "myorg",
+		"custom.my_integration.field": "value",
+	}
+
+	for key, val := range namespaces {
+		err := store.SetConfig(ctx, key, val)
+		if err != nil {
+			t.Fatalf("SetConfig for %s failed: %v", key, err)
+		}
+	}
+
+	// Verify all set correctly
+	for key, expected := range namespaces {
+		value, err := store.GetConfig(ctx, key)
+		if err != nil {
+			t.Fatalf("GetConfig for %s failed: %v", key, err)
+		}
+		if value != expected {
+			t.Errorf("Expected '%s' for %s, got '%s'", expected, key, value)
+		}
+	}
+
+	// Test GetAllConfig returns all
+	config, err := store.GetAllConfig(ctx)
+	if err != nil {
+		t.Fatalf("GetAllConfig failed: %v", err)
+	}
+
+	for key, expected := range namespaces {
+		if config[key] != expected {
+			t.Errorf("Expected '%s' for %s in GetAllConfig, got '%s'", expected, key, config[key])
+		}
+	}
+}
+
+// setupTestDB creates a temporary test database
+func setupTestDB(t *testing.T) (*sqlite.SQLiteStorage, func()) {
+	tmpDir, err := os.MkdirTemp("", "bd-test-config-*")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+
+	testDB := filepath.Join(tmpDir, "test.db")
+	store, err := sqlite.New(testDB)
+	if err != nil {
+		os.RemoveAll(tmpDir)
+		t.Fatalf("Failed to create test database: %v", err)
+	}
+
+	cleanup := func() {
+		store.Close()
+		os.RemoveAll(tmpDir)
+	}
+
+	return store, cleanup
+}