fix(discovery): report syntax errors in candidate test files

[cayasde]

Reproduction

Create lutest.toml:

[discovery.lute]
require = "@lutest_release"
roots = ["src"]

Create src/broken.luau:

local t = require '@lutest_release'

t.test('has invalid syntax', function()
    assert(true)

Then run from the config directory:

lutest test --config lutest.toml
lutest todo --config lutest.toml

Actual behavior

• test reports No test files found.
• todo exits with code 0 and reports No todo tests.
• test --dry-run reports zero files.

The syntax error is not shown in any of these paths.

Expected behavior

If static discovery sees a file that imports the configured Lutest library but cannot parse it, Lutest should surface a configuration or test-file parse error with the file path and parser details. It should not silently omit the file or let todo succeed.