fix: AI terminal init, Shift+Tab nav, code block rendering, command filtering

- Fix AI terminal not initializing (wait for shell col visibility, remove offsetHeight guard)
- Add Shift+Tab to cycle between shell terminals
- Handle unclosed code blocks in renderContent (Shell + Studio)
- Filter irrelevant commands from history (short/non-alpha backend + expanded frontend exclude list)

💘 Generated with Crush

Assisted-by: GLM-5.1 via Crush <crush@charm.land>

internal/api/handlers_info.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"time"
 
@@ -553,10 +554,11 @@ func (s *Server) handleRecentCommands(w http.ResponseWriter, r *http.Request) {
 			shell = "zsh"
 		}
 		lines := strings.Split(string(data), "\n")
-		start := len(lines) - 25
+		start := len(lines) - 50
 		if start < 0 {
 			start = 0
 		}
+
 		for i := len(lines) - 1; i >= start; i-- {
 			line := strings.TrimSpace(lines[i])
 			if line == "" || strings.HasPrefix(line, "#") {
@@ -573,6 +575,15 @@ func (s *Server) handleRecentCommands(w http.ResponseWriter, r *http.Request) {
 			if line == "" {
 				continue
 			}
+
+			base := strings.Fields(line)[0]
+			if len(base) < 2 {
+				continue
+			}
+			if !regexp.MustCompile(`^[a-zA-Z@./]`).MatchString(base) {
+				continue
+			}
+
 			entries = append(entries, cmdEntry{Cmd: line, Shell: shell})
 		}
 	}