refactor: improve AI event handling and conflict display in chat

- AI fetches events on-demand via callbacks for better efficiency
- Add conflict detection with warning display when proposing overlapping events
- Improve event search and display in chat interface
- Load full chat history for display while limiting AI context

apps/server/src/logging/Logged.ts

@@ -4,7 +4,7 @@ import { createLogger } from "./logger";
  * Summarize args for logging to avoid huge log entries.
  * - Arrays: show length only
  * - Long strings: truncate
- * - Objects with conversationHistory/existingEvents: summarize
+ * - Objects with conversationHistory: summarize
  */
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 function summarizeArgs(args: any[]): any[] {
@@ -31,8 +31,6 @@ function summarizeValue(value: any, depth = 0): any {
     for (const [key, val] of Object.entries(value)) {
       if (key === "conversationHistory" && Array.isArray(val)) {
         summarized[key] = `[${val.length} messages]`;
-      } else if (key === "existingEvents" && Array.isArray(val)) {
-        summarized[key] = `[${val.length} events]`;
       } else if (key === "proposedChanges" && Array.isArray(val)) {
         // Log full proposedChanges for debugging AI issues
         summarized[key] = val.map((p) => summarizeValue(p, depth + 1));