fix: chat code block isInsertable language comparison

[datlechin]

Summary

Hot-fix for compile error introduced by #1077.

AIChatCodeBlockView.isInsertable compared treeSitterLanguage.id != .default. Swift's type inference resolved .default to TaskPriority.default instead of TreeSitterLanguage, producing:

Cannot convert value of type 'TreeSitterLanguage' to expected argument type 'TaskPriority'

Fix: qualify the comparison with CodeLanguage.default.id so both sides are explicitly TreeSitterLanguage.

Test plan

• Build the project. The error at AIChatCodeBlockView.swift:153 no longer fires.
• Open a chat code block produced by the AI. The Insert button is enabled when the language is recognized (sql/javascript/bash) and disabled for plain text.

[chatgpt-codex-connector]

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