view: the edit range of an expression that starts with ( drops the ( #2062

Found in the review of #2057, which adds the experimental view. It does not block that PR; #2059 fixed the findings that did. Paths refer to #2059's head.

Problem

The view model's expression range (expr, expr_range) starts after an opening (, so an edit through the range leaves the ( behind.

definition_span in crates/graphcal-project/src/view_model/project.rs builds the range from the IR span of the definition and trims the text by hand. The IR span of a parenthesized expression does not include the (.

Reproduction

node a: Dimensionless = 1.0;
node y: Dimensionless = (@a + 2.0) * 3.0;
node z: Dimensionless = (@a);
assert ok = (@y) > 0.0;

graphcal view reports expr as @a + 2.0) * 3.0, @a) and @y) > 0.0. Editing z to 5.0 in the view writes (5.0;.

Impact

• The GitHub host compiles the result, sees the syntax error, and rolls the edit back.
• The VS Code host writes the edit into the user's document. Fix this before the VS Code integration is enabled.

Proposed fix

• Carry the syntactic range of the expression after =, parentheses included, from the AST to the IR.
• Delete the text trimming in definition_span.
• Test single and nested parentheses, multi-line expressions, comments, UTF-16 columns, and param, const, node and assert.