fix: token persistence, context windows, CSS tables/bullets/hr, image attachments

- Fix token count reset on app restart: persist realTokens in conversation.json
- Fix token/context window values: Studio 150K (summarize at 120K), Terminal 100K
- Fix table rendering in terminal tab: correct thead/tbody display model
- Fix copy button always top-right in Studio code blocks
- Add markdown horizontal rule (---) support in Studio and Terminal
- Fix bullet list double dot: remove CSS ::before duplicate bullet point
- Add image attachments support (VLM description, file mentions @file.ext)
- Add sudo detection with cache (sync.Once)
- Fix message content serialization (TextContent wrapper)
- Guide AI to use read_file instead of cat in studio prompt

💘 Generated with Crush

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

internal/agent/definitions.go

@@ -7,9 +7,32 @@ import (
 	"os/exec"
 	"path/filepath"
 	"strings"
+	"sync"
 	"time"
 )
 
+var (
+	sudoCache     bool
+	sudoCacheSet  bool
+	sudoCacheOnce sync.Once
+)
+
+func NeedsSudoPassword() bool {
+	sudoCacheOnce.Do(func() {
+		if os.Geteuid() == 0 {
+			ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+			defer cancel()
+			err := exec.CommandContext(ctx, "sudo", "-n", "true").Run()
+			sudoCacheSet = true
+			sudoCache = err != nil
+		} else {
+			sudoCache = true
+			sudoCacheSet = true
+		}
+	})
+	return sudoCache
+}
+
 type TerminalParams struct {
 	Command string `json:"command" description:"The shell command to execute"`
 	Timeout int    `json:"timeout,omitempty" description:"Timeout in seconds (default 60, max 300)"`
@@ -30,7 +53,7 @@ func NewTerminalTool() (*ToolDefinition, error) {
 				return TextErrorResponse("command is required"), nil
 			}
 
-			if os.Geteuid() != 0 {
+			if NeedsSudoPassword() {
 				trimmed := strings.TrimSpace(p.Command)
 				lower := strings.ToLower(trimmed)
 				if strings.HasPrefix(lower, "sudo ") || strings.HasPrefix(lower, "doas ") || strings.HasPrefix(lower, "run0 ") || strings.HasPrefix(lower, "pkexec ") {