refactor(api): split monolithic handlers.go into focused modules

Break down the 627-line handlers.go into specialized modules:
- handlers_chat.go: chat and streaming endpoints
- handlers_config.go: configuration endpoints
- handlers_common.go: shared utilities
- handlers_info.go: info and status endpoints
- handlers_terminal.go: terminal/shell endpoints
- handlers_tools.go: tool-related endpoints

Also includes config improvements, orchestrator enhancements, and
web component updates.

💘 Generated with Crush

Assisted-by: MiniMax-M2.7 via Crush <crush@charm.land>

internal/scanner/scanner.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
+	"path/filepath"
 	"regexp"
 	"strings"
 	"sync"
@@ -169,7 +170,7 @@ func checkShellSetup() bool {
 	home, _ := os.UserHomeDir()
 	rcFiles := []string{".bashrc", ".zshrc", ".config/fish/config.fish"}
 	for _, f := range rcFiles {
-		data, err := os.ReadFile(home + "/" + f)
+		data, err := os.ReadFile(filepath.Join(home, f))
 		if err != nil {
 			continue
 		}