fix: fall back to issue.assignee on Forgejo for assignee trigger

Forgejo's issues/assigned webhook payload doesn't include a top-level
assignee object. The assignee is only available under issue.assignee.
Fall back to that field when payload.assignee is missing.

Also removes M5 debug logging.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/entrypoints/run.ts

@@ -187,30 +187,6 @@ async function run() {
       }
     }
 
-    // === M5 DEBUG START ===
-    console.log(`[M5 DEBUG] eventName: ${context.eventName}`);
-    console.log(`[M5 DEBUG] eventAction: ${context.eventAction}`);
-    console.log(
-      `[M5 DEBUG] assigneeTrigger: "${context.inputs?.assigneeTrigger}"`,
-    );
-    console.log(
-      `[M5 DEBUG] ASSIGNEE_TRIGGER env: "${process.env.ASSIGNEE_TRIGGER}"`,
-    );
-    if (isEntityContext(context)) {
-      const payload = context.payload as Record<string, any>;
-      console.log(
-        `[M5 DEBUG] payload.assignee: ${JSON.stringify(payload.assignee)}`,
-      );
-      console.log(
-        `[M5 DEBUG] payload.issue.assignee: ${JSON.stringify(payload.issue?.assignee)}`,
-      );
-      console.log(
-        `[M5 DEBUG] payload.issue.assignees: ${JSON.stringify(payload.issue?.assignees?.map((a: any) => a.login))}`,
-      );
-      console.log(`[M5 DEBUG] payload.action: ${payload.action}`);
-    }
-    // === M5 DEBUG END ===
-
     // Check trigger conditions
     const containsTrigger =
       modeName === "tag"