fix: stop firing SessionStart hook on --resume

Resumed sessions already have injected context in their conversation
history. Re-firing the hook was redundant and could cause issues.
The hook now fires only on startup, clear, and compact.

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

hooks/hooks.json

@@ -2,7 +2,7 @@
   "hooks": {
     "SessionStart": [
       {
-        "matcher": "startup|resume|clear|compact",
+        "matcher": "startup|clear|compact",
         "hooks": [
           {
             "type": "command",