fix(lang): track Solidity modifier invocations as decorators

[sanskar717]

Summary

Adds Solidity modifier_invocation support to the existing Solidity language specification so modifier usages such as onlyOwner are tracked as decorators in the code graph.

Changes

• Added solidity_decorator_types with modifier_invocation
• Wired it into CBM_LANG_SOLIDITY
• Enables modifier definitions and invocations such as onlyOwner to be tracked correctly

Verification

Verified locally with search_code using onlyOwner:

• Found the modifier definition
• Found the onlyOwner invocation on withdraw

Relation to #1754

The issue proposes adding Solidity parser support. Since Solidity grammar is already vendored through Tree-sitter, this change extends the existing parsing path without introducing a Node.js runtime or JavaScript dependency.

This PR specifically fixes the missing modifier/decorator tracking in the current Solidity support.

[github-actions]

Thanks for opening this — it has been seen, and it is queued.

This note is automated, but it is not a brush-off: it exists so you know where your PR stands instead of having to guess from silence.

Current review status: working through a backlog. 0.9.1-rc.1 is out, so the release freeze that held reviews is over — but it left a large queue of open pull requests behind it, and we are reading through them oldest-first. The background is in discussion #1144.

What that means for this PR, concretely:

• It will not be closed for inactivity. No stale bot touches pull requests here.
• It may still sit a while before a human reads it. That is on us, not on you.
• Older PRs are read first, so a recent one is not being skipped — it is behind a queue.

Things that will genuinely speed it up whenever review does happen:

• Keep it rebased on main — the tree is moving quickly right now, and a conflicting branch cannot be reviewed as the diff you intended.
• Get CI green, or say which failures you believe are pre-existing.
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If this fixes a bug, a reproduction we can run is worth more than a description of the symptom.

Thanks for contributing, and sorry in advance for the wait.

[sanskar717]

The issue specifically requested @solidity-parser/parser (JS). Since this project is pure C and uses a single-binary setup, I completed the existing tree-sitter-solidity path instead, focusing on modifier/decorator tracking.

Verified using search_code with onlyOwner, covering both the modifier definition and its invocations.