Fix .idea directory not being ignored due to allowlist pattern

- Move .idea/ ignore rule after the !*/ allowlist directive
- Add **/.idea/ pattern to catch nested occurrences
- The !*/ rule was re-including directories, overriding the earlier ignore

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

.gitignore

@@ -94,6 +94,10 @@ cmd/benchmark/data
 !libsecp256k1.so
 # ...even if they are in subdirectories
 !*/
+
+# Re-ignore IDE directories (must come after !*/)
+.idea/
+**/.idea/
 /blocklist.json
 /gui/gui/main.wasm
 /gui/gui/index.html