fix: disable spell-check in URLs

[troiganto]

Summary

Back when hyperlinks still used extmarks, we disabled spell-checking for the URL part (d383f5c). This must've gotten lost when switching over to treesitter queries.

This PR disables spell-checking again in highlights.scm.

Related Issues

Related to #547

Changes

• Annotate the URL portion of the two relevant queries ([[url]] and [[url][description]]) with @nospell.

Checklist

I confirm that I have:

• Followed the Conventional Commits specification (e.g., feat: add new feature, fix: correct bug, docs: update documentation).
• My PR title also follows the conventional commits specification.
• Updated relevant documentation, if necessary.
• Thoroughly tested my changes.
• Added tests (if applicable) and verified existing tests pass with
  make test.
• Checked for breaking changes and documented them, if any.

[troiganto]

Looks like a spurious error, the clocking merely took a second longer than usual:

 Fail	||	Clock should clock out first entry from same file once second entry is clocked in	
            ...ner/work/orgmode/orgmode/tests/plenary/ui/clock_spec.lua:76: Expected objects to be the same.
            Passed in:
            (string) '(Org) [0:01] (Second clocked in)'
            Expected:
            (string) '(Org) [0:00] (Second clocked in)'
            
            stack traceback:
            	...ner/work/orgmode/orgmode/tests/plenary/ui/clock_spec.lua:76: in function <...ner/work/orgmode/orgmode/tests/plenary/ui/clock_spec.lua:38>
            	
Fail	||	Clock should clock out entry from another file once entry is clocked in	
            ...ner/work/orgmode/orgmode/tests/plenary/ui/clock_spec.lua:100: Expected objects to be the same.
            Passed in:
            (string) '  CLOCK: [2025-05-12 Mon 10:02]--[2025-05-12 Mon 10:03] => 0:01'
            Expected:
            (string) '  CLOCK: [2025-05-12 Mon 10:03]--[2025-05-12 Mon 10:03] => 0:00'
            
            stack traceback:
            	...ner/work/orgmode/orgmode/tests/plenary/ui/clock_spec.lua:100: in function <...ner/work/orgmode/orgmode/tests/plenary/ui/clock_spec.lua:79>

[kristijanhusak]

Thanks!