refactor(events): expand eventType taxonomy with central config

Replaces the four-value enum (community/workshop/social/showcase) with
seven values: talk, workshop, community-meetup, coworking, peer-session,
skills-share, info-session. Default is now community-meetup.

Adds app/config/eventTypes.js as the single source of truth for value→label
mapping. Updates the model enum, seed scripts, and admin event list/filter
+ admin dashboard to read from it via EVENT_TYPES and eventTypeLabel().

scripts/seed-series-events.js

@@ -149,7 +149,7 @@ async function seedSeriesEvents() {
           "Our monthly community meetup provides a relaxed environment to share your projects, get feedback, and connect with other developers interested in cooperative models.",
         startDate: new Date("2024-10-12T18:00:00.000Z"),
         endDate: new Date("2024-10-12T20:00:00.000Z"),
-        eventType: "community",
+        eventType: "community-meetup",
         location: "#community-meetup",
         isOnline: true,
         membersOnly: false,
@@ -176,7 +176,7 @@ async function seedSeriesEvents() {
           "Our monthly community meetup provides a relaxed environment to share your projects, get feedback, and connect with other developers interested in cooperative models.",
         startDate: new Date("2024-11-09T18:00:00.000Z"),
         endDate: new Date("2024-11-09T20:00:00.000Z"),
-        eventType: "community",
+        eventType: "community-meetup",
         location: "#community-meetup",
         isOnline: true,
         membersOnly: false,