Auto-lint: convert .map(lambda → JSX) to list comprehension syntax (W3039)

[SupulHeshan]

Summary

Adds a new auto-lint rule W3039 (map-lambda-to-comprehension) that automatically
converts verbose React-style .map() lambda patterns to Jac's native JSX comprehension syntax.

Before:

items.map(lambda item: any, idx: int -> any {
    return <li key={idx}>{item.name}</li>;
})

After:

[<li key={idx}>{item.name}</li> for (idx, item) in enumerate(items)]

When the lambda has no index parameter, the simpler form is used:

<li>{item.name}</li> for item in items]

Changes

• diagnostics.jac - adds W3039 warning with kebab alias map-lambda-to-comprehension
• jac_auto_lint_pass.jac - imports W3039, declares _make_name_node and _convert_map_to_comprehension
• jac_auto_lint_pass.impl.jac - implements the detection + AST rewrite; wired into exit_func_call

Pattern matched

• Target is <expr>.map(lambda ...)
• Lambda has a block body ({ ... }) with exactly one statement: return <JsxElement>
• Lambdas with pre-computation (multiple statements before the return) are intentionally skipped
• A second int-typed parameter is recognized as the loop index → enumerate() is injected automatically

[Copilot]

Pull request overview

Adds a new auto-lint rule W3039 (map-lambda-to-comprehension) to rewrite React-style .map(lambda ... { return <jsx>; }) patterns into Jac list comprehension JSX syntax, improving idiomatic Jac output during auto-lint formatting.

Changes:

• Adds W3039 diagnostic text + kebab-case alias mapping.
• Extends JacAutoLintPass API with helpers for building synthetic Name nodes and performing the .map(...) → ListCompr AST rewrite.
• Wires the conversion into exit_func_call so it runs during auto-lint formatting.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
jac/jaclang/jac0core/diagnostics.jac	Defines W3039 warning message and adds alias mapping for config/back-compat.
jac/jaclang/compiler/passes/tool/jac_auto_lint_pass.jac	Imports W3039 and declares the new conversion helpers on the pass.
jac/jaclang/compiler/passes/tool/impl/jac_auto_lint_pass.impl.jac	Implements detection + AST rewrite and invokes it from exit_func_call.