fix(core): bound search tool execution

[opencode-agent]

Summary

• add a 30-second deadline to the interactive glob and grep tools
• return a focused error that tells the model to narrow the path or pattern

Fixes #39208

Checks

• bun test test/ripgrep.test.ts test/tool-search.test.ts
• bun typecheck
• manually verified with a non-terminating ripgrep harness that timeout returns the expected error and terminates the child process
• bun test --only-failures (host environment has no node executable; unrelated cross-spawn and process-contention tests fail)

Requested by: @rekram1-node (Aiden Cline via Slack)