feat(jira): issue_type=Epic + AssigneeMap + CLI resync-jira-fields

Cambios:
- jiraConfig: nuevo campo AssigneeMap (kanban_user_id -> jira_accountId).
- jiraHandler.create() y update(): aplican fields.assignee={accountId} cuando
  card.AssigneeID esta en el map. NO se borra el assignee de Jira cuando no
  hay mapeo (evita pisar asignaciones manuales).
- resolveJiraAssignee: helper compartido.
- seed-jira-data: cambio issue_type default Tarea Tecnica -> Epic (board 33
  filtra issuetype=Epic). assignee_map inyectada con 3 mapeos confirmados:
    egutierrez (Enmaa)  -> 712020:2cf3b82f-... (Enmanuel Gutierrez Perez)
    amassaguer (alfon)  -> 712020:3f3ca9e1-... (Alfonso Massaguer Gomez)
    ntajuelo   (Nat)    -> 712020:feb5f7c5-... (Natalia Tajuelo Gomez)
- Nueva CLI 'kanban resync-jira-fields' con flags
    --set-issuetype/--set-assignee/--set-labels/--dry-run/--limit/--batch-size/--pause-sec
  Idempotente. PUT /rest/api/3/issue/{key} con los fields del config actual.
  Usado para patchear las 127 issues ya creadas con Tarea Tecnica -> Epic +
  assignee (donde mapea).
- Ejecutado: 127/127 OK, 0 fail. Board 33 ahora muestra 219 issues totales
  (92 Epics previas + 127 nuevas). Sample verificado contra Jira REST API.

backend/seed_jira.go

@@ -70,16 +70,26 @@ func runSeedJiraData(args []string) error {
 	labelsMap := map[string][]string{
 		"Bloqueadas": {"blocked"},
 	}
+	// kanban user_id -> Jira accountId. Resolved via Jira /user/search; the
+	// three current data-team users keep stable IDs across sessions. New
+	// users added to the kanban must be added here (or the seed re-run with
+	// --pass-prefix overrides) so the dispatcher can route the assignee.
+	assigneeMap := map[string]string{
+		"6a75edc6e99d8405": "712020:2cf3b82f-47d6-4597-b0e9-ffaaf3a07cc3", // Enmaa  -> Enmanuel Gutierrez Perez
+		"039c97acf1869393": "712020:3f3ca9e1-c86e-445e-979a-bc7b82a4f45d", // alfon  -> Alfonso Massaguer Gómez
+		"9e91db261084d529": "712020:feb5f7c5-7643-4381-977c-d83c95ba4955", // Nat    -> Natalia Tajuelo Gomez
+	}
 
 	cfg := JSONValue{
-		"base_url":    baseURL,
-		"email":       email,
-		"api_token":   token,
-		"project_key": *project,
-		"board_id":    *board,
-		"issue_type":  "Tarea Técnica",
-		"status_map":  statusMap,
-		"labels_map":  labelsMap,
+		"base_url":     baseURL,
+		"email":        email,
+		"api_token":    token,
+		"project_key":  *project,
+		"board_id":     *board,
+		"issue_type":   "Epic",
+		"status_map":   statusMap,
+		"labels_map":   labelsMap,
+		"assignee_map": assigneeMap,
 	}
 
 	// Upsert by name. Module name is the human-friendly identifier; we treat