Fix HX-Location replace option

[scriptogre]

replace is ignored because HX-Location always adds the default push option:

HX-Location: {"path":"/dashboard","replace":"/dashboard"}

Expected: replace the current history entry
Actual:   push a new history entry

The same format check misclassifies URLs with commas and minimal HCON:

Value	Expected	Actual
/files/a,b	Plain URL	HCON
path:/search	HCON	Plain URL

Changes

1. Default to push: 'true' only when push and replace are absent.

2. Use parsed path to distinguish HCON from a plain URL:

   /files/a,b    -> /files/a,b
   path:/search  -> { path: '/search' }
   

3. Rewrite the HX-Location reference page.

4. Add regression tests.