feat: Phase 4 port Oracle, Meaning, UNE, and Dice

Ports the four core Mythic GME tools from reference/index.html into
the modular structure. Fate Check and Random Event Check preserve
the exact probability matrix and roll logic, now reading chaos
factor live from the active campaign instead of local state. Meaning
and UNE tables are served from data/tables/ via a new tables route.
UNE motivation uses the published verb+noun tables instead of the
reference's flattened phrase list. Dice (pool builder, custom roll,
percentile, ability score) is ported verbatim as pure frontend logic.

public/js/api.js

@@ -49,3 +49,7 @@ export function deleteCampaign(id) {
 export function getSystems() {
   return request('/systems');
 }
+
+export function getTable(name) {
+  return request(`/tables/${name}`);
+}