chore(gitignore): ignore .opencode/magic-context.jsonc

The Magic Context plugin writes per-project config to .opencode/magic-context.jsonc.
It's a user-personal toggle (e.g. {"ctx_reduce_enabled": true}), not project state
shared across contributors. Treat it like .opencode/dumps and keep it out of git.

Author: ualtinok

.gitignore

@@ -47,6 +47,7 @@ ts-bench/
 # Benchmark configs (may contain API keys)
 benchmarks/configs/
 .opencode/dumps
+.opencode/magic-context.jsonc
 codedb.snapshot
 benchmarks/search-bench-results.json