feat(issues): S4b frontend — open-issues lists + issue plumbing

- types/note.ts: Note gains systems? + arose_from_id?; TaskKind includes 'issue'.
- stores/tasks.ts: create/update accept IssueFields (kind/system_ids/arose_from_id).
- api/systems.ts: getProjectIssues + TaskLike.
- DashboardView.vue: 'Open issues' rail section from dashboard.open_issues
  (links to /tasks/<id>, project + status).
- SystemsSection.vue (project Systems tab): 'Open issues' list via getProjectIssues,
  with system chips, links to /tasks/<id>. Both reuse existing CSS tokens.

Issue-editor controls (kind selector / system multi-select / arose-from picker
in WorkspaceTaskPanel) are the remaining S4b piece. NEEDS operator browser
verification (CI typechecks only).

Refs plan 825 (S4b frontend — lists).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/types/note.ts

@@ -1,5 +1,8 @@
+import type { System } from "@/api/systems";
+
 export type TaskStatus = "todo" | "in_progress" | "done" | "cancelled";
 export type TaskPriority = "none" | "low" | "medium" | "high";
+export type TaskKind = "work" | "plan" | "issue";
 export type NoteType = "note" | "person" | "place" | "list" | "process";
 
 export interface Note {
@@ -22,7 +25,9 @@ export interface Note {
   recurrence_next_spawn_at: string | null;
   is_task: boolean;
   note_type: NoteType;
-  task_kind?: "work" | "plan";
+  task_kind?: TaskKind;
+  systems?: System[];
+  arose_from_id?: number | null;
   metadata: Record<string, string>;
   created_at: string;
   updated_at: string;