fix: harden identity, live access, drafts and setup (review only)

Source-reviewed hardening changes and regression tests. UNBUILT / UNTESTED: not a deployable release. Go formatting, compilation, automated regression tests, full frontend validation and staging acceptance remain required. See docs/hardening/VALIDATION.md. Main remains the original clean snapshot; no upstream Git history imported.

internal/pkg/dto/dto.go

@@ -1,6 +1,11 @@
+// Modified in the independent hardening fork; see docs/hardening.
+
 package dto
 
-import "agent-desk/internal/pkg/enums"
+import (
+	"agent-desk/internal/pkg/enums"
+	"time"
+)
 
 type AuthPrincipal struct {
 	UserID      int64
@@ -11,16 +16,22 @@ type AuthPrincipal struct {
 	Status      enums.Status
 	Roles       []string
 	Permissions []string
+
+	// Session metadata stays internal and binds long-lived connections to the
+	// original login session and its absolute deadline.
+	LoginSessionID int64     `json:"-"`
+	ExpiresAt      time.Time `json:"-"`
 }
 
 type WebChannelConfig struct {
-	Title           string   `json:"title"`
-	Subtitle        string   `json:"subtitle"`
-	ThemeColor      string   `json:"themeColor"`
-	Position        string   `json:"position"`
-	Width           string   `json:"width"`
-	UserTokenSecret string   `json:"userTokenSecret,omitempty"`
-	PromptStarters  []string `json:"promptStarters,omitempty"`
+	Title                 string   `json:"title"`
+	Subtitle              string   `json:"subtitle"`
+	ThemeColor            string   `json:"themeColor"`
+	Position              string   `json:"position"`
+	Width                 string   `json:"width"`
+	UserTokenSecret       string   `json:"userTokenSecret,omitempty"`
+	RequireSignedIdentity bool     `json:"requireSignedIdentity,omitempty"`
+	PromptStarters        []string `json:"promptStarters,omitempty"`
 }
 
 type TelegramChannelConfig struct {