chore(gitignore): ignore Agda/Zig/bench/priv build artifacts

Stops six untracked build outputs from cluttering the tree: Agda .agdai
interface files, benches/eval_tmp + eval_results.json, demo guest wasm,
priv/snif_eval.json, and zig/buffer_abi_build. All are regenerated by the
proof/bench/build recipes.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

.gitignore

@@ -114,3 +114,11 @@ deps/
 .cache/
 build/
 dist/
+
+# Proof + guest build artifacts (snifs)
+*.agdai
+/benches/eval_tmp/
+/benches/eval_results.json
+/demo/priv/*.wasm
+/priv/snif_eval.json
+/zig/buffer_abi_build/