Address review feedback: In full-path XPath generation, elements with
IDs were producing bare predicates like `[@id='x']` which creates
invalid XPath steps like `//body/[@id='main']`. Now emits `*[@id='x']`
for full-path mode (e.g. `//body/*[@id='main']/*[@id='target']`).
Short-path XPath mode unchanged — still uses `//*[@id='x']` prefix.
Also added XPath evaluation assertion to the regression test to verify
the generated selector actually selects the correct element.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
When generating full-path CSS/XPath selectors, elements with id
attributes had their selector appended twice — once in the id branch
(line 30) and again unconditionally (line 50).
This produced selectors like 'body > #main > #main > #target > #target'
instead of the correct 'body > #main > #target'.
Move the append into the else branch so it only fires for elements
without an id (elements with id already append in the if branch).
Includes 2 regression tests.
