feat(feedback): in-app user feedback with admin review and account roles

User-facing Feedback screen (Settings -> Info, registered accounts only): a
message (<=1024 runes) plus one optional attachment, an anti-spam gate (one
unreviewed message at a time), and the operator's inline reply with a
Settings/Info badge. Server-rendered admin console section (/_gm/feedback):
unread/read/archived queue with per-user search, detail with read/reply/
archive/delete/delete-all, safe attachment serving (nosniff, images inline via
<img>, others download-only). Introduces account_roles, the first per-account
role table; feedback_banned blocks only feedback submission, granted/revoked
from /users and the delete-with-block action.

- migration 00004_feedback (feedback_messages + account_roles) + jetgen
- backend internal/feedback (store+service), internal/account/roles.go
- wire: FlatBuffers feedback.submit/get/unread; gateway guest gate (Op.NonGuest,
  is_guest via session resolve) -> guest_forbidden before any backend call
- reply push reuses NotificationEvent with a new admin_reply sub-kind
- UI: /feedback route + screen, attachment picker, badge, channel detection, i18n
- tests: feedback unit (Go+UI), gateway guest-gate, inttest lifecycle, e2e
- docs: PLAN stage 19, ARCHITECTURE s15, FUNCTIONAL(+ru), TESTING, READMEs

backend/internal/adminconsole/views.go

@@ -42,6 +42,7 @@ type DashboardView struct {
 	Games          int
 	ActiveGames    int
 	OpenComplaints int
+	OpenFeedback   int
 	PendingChanges int
 	// ActiveVersion is the dictionary version new games pin (the persisted active
 	// version), distinct from the per-variant resident versions.
@@ -142,6 +143,10 @@ type UserDetailView struct {
 	// form; Reasons is the operator-editable reason picklist offered in the block form.
 	Suspension SuspensionView
 	Reasons    []ReasonOption
+	// Roles is the account's current roles (each revocable); KnownRoles is the set the
+	// grant form offers. The first role is the feedback ban (see internal/account).
+	Roles      []string
+	KnownRoles []string
 }
 
 // SuspensionView is an account's current manual-block state shown on the user card: whether it
@@ -362,3 +367,58 @@ type MessageView struct {
 	Body    string
 	Back    string
 }
+
+// FeedbackView is the paginated user-feedback queue. Status is the active
+// unread/read/archived filter; NameMask/ExtMask are the sender glob filters;
+// UserID pins the list to one account (the per-user link from /users);
+// FilterQuery is the active filters URL-encoded for the pager links (already
+// escaped, hence template.URL — see UsersView.FilterQuery).
+type FeedbackView struct {
+	Items       []FeedbackRow
+	Status      string
+	NameMask    string
+	ExtMask     string
+	UserID      string
+	Pager       Pager
+	FilterQuery template.URL
+}
+
+// FeedbackRow is one feedback message in the queue: its sender (linked to the user
+// card), source, channel, whether it has an attachment / a reply, its state and
+// time.
+type FeedbackRow struct {
+	ID            string
+	AccountID     string
+	SenderName    string
+	Source        string
+	Channel       string
+	HasAttachment bool
+	Read          bool
+	Replied       bool
+	Archived      bool
+	CreatedAt     string
+}
+
+// FeedbackDetailView is one feedback message with its body, attachment, state and
+// the reply / archive / delete forms. Body, AttachmentName, SenderName and IP are
+// user-controlled and rendered as plain auto-escaped text. IsImage gates the inline
+// <img> preview; Banned shows whether the sender already holds the feedback ban.
+type FeedbackDetailView struct {
+	ID             string
+	AccountID      string
+	SenderName     string
+	Source         string
+	Channel        string
+	IP             string
+	Body           string
+	HasAttachment  bool
+	AttachmentName string
+	IsImage        bool
+	Read           bool
+	Archived       bool
+	Replied        bool
+	ReplyBody      string
+	RepliedAt      string
+	CreatedAt      string
+	Banned         bool
+}