feat: cfg-based unreachable diagnostics

[hongjr03]

This depends on and should be merged after #2302.

Add CFG construction and basic graph analysis interfaces based on the Typst AST in tinymist-analysis; rewrite the unreachable diagnostic in tinymist-lint using CFG reachability to improve span coverage and support reporting multiple consecutive unreachable segments; and add snapshot tests for unreachable in tinymist-query.

[gemini-code-assist]

Summary of Changes

Hello @hongjr03, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a robust Control-Flow Graph (CFG) analysis capability for Typst code, which is then immediately applied to significantly improve the accuracy and detail of unreachable code detection within the tinymist-lint component. The changes also include a substantial refactoring of the diagnostic reporting system, allowing for distinct handling of compiler and lint diagnostics, and a new modular 'hook' system for managing various post-compilation processes like preview and export. These enhancements lead to more precise and informative diagnostics for users and a more maintainable codebase for future development.

Highlights

• Control-Flow Graph (CFG) Implementation: A new module tinymist-analysis/src/cfg has been added to construct and analyze Control-Flow Graphs directly from the Typst Abstract Syntax Tree (AST). This includes definitions for basic blocks, terminators, and graph analysis utilities like dominators and reachable blocks.
• Enhanced Unreachable Code Diagnostics: The unreachable code diagnostic in tinymist-lint has been rewritten to leverage the new CFG analysis. This significantly improves span coverage, allowing for more precise highlighting of unreachable code, and supports reporting multiple consecutive unreachable segments.
• Modular Diagnostic Publishing: The diagnostic publishing mechanism in tinymist has been refactored to differentiate between compiler-generated and lint-generated diagnostics. This is achieved through the introduction of DiagKind and DiagKey, allowing for more granular control and clearer categorization of issues presented to the editor.
• Compile Hook System: A new CompileHook trait and associated implementations (DiagHook, LintHook, PreviewHook, ExportHook) have been introduced. This modularizes the handling of compilation events, making the CompileHandlerImpl more extensible and maintainable by decoupling various post-compilation tasks.
• Comprehensive Snapshot Tests: Numerous new snapshot tests have been added in tinymist-query to validate the accuracy and behavior of the enhanced unreachable code diagnostics across various Typst code patterns, including loops, conditionals, and return statements.

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[gemini-code-assist]

Code Review

This pull request introduces a significant improvement to unreachable code detection by implementing a CFG-based analysis. The new cfg module in tinymist-analysis is well-structured, and the implementation of CFG construction and dominator analysis appears solid. The linter in tinymist-lint is cleanly updated to use this new analysis.

A major highlight of this PR is the refactoring in tinymist to use a CompileHook trait. This greatly improves modularity by separating concerns like diagnostics, linting, preview updates, and exports into their own hooks. This is an excellent architectural improvement.

The addition of comprehensive tests for various unreachable code scenarios is also very valuable.

I have a few minor suggestions for improving code clarity and consistency, but overall this is a high-quality contribution.

[hongjr03]

Closed in favor of #2321.