Fix nested template function depth tracking

[674019130]

Summary

Count recursive template-function argument evaluation toward the existing render depth budget. This prevents deeply nested function arguments from bypassing MAX_DEPTH, while preserving normal nesting and the established Throw and ReturnEmpty behaviors.

Root cause

The Val::Fn argument resolver recursively called render_value with the unchanged depth. Unlike variable and returned-template recursion, a chain such as f(value=f(value=...)) could therefore descend without reaching the guard in render.

Submission

• This PR is a bug fix.
• If this PR is not a bug fix, I linked the feedback item where @gschier explicitly gave me permission to work on it.
• I have read and followed CONTRIBUTING.md.
• I tested this change locally.
• I added or updated tests, or tests are not reasonable for this change.
• I added screenshots or recordings, or this change does not affect the UI.

Explicit permission feedback item (required if not a bug fix):

Not required; this is a bug fix.

Related

• https://yaak.app/feedback/posts/three-unguarded-recursion-cache-paths-in-main-1b28dfd
• This PR addresses only the “Nested function args → MAX_DEPTH bypass” item.

Verification

• cargo test -p yaak-templates — 92 unit tests and all doc tests passed
• cargo check -p yaak-templates
• cargo fmt -p yaak-templates -- --check
• npm test
• npm run lint — passed with two existing TypeScript warnings outside this change

Attribution

Implemented and verified with OpenAI Codex.

[github-actions]

Thanks for the PR. This appears to match Yaak's contribution policy and is awaiting review by @gschier.

This only means the PR is in scope for review. It does not mean the change has been reviewed or accepted for merge.