QueryOne!: Support /./ to immediately get term + -default when 0 results

[osnr]

Saves a lot of code repetition -- we've been using lindex, dict getdef, and list length comparisons very repetitively when querying imperatively.

See Discord: https://discord.com/channels/956758212152025098/956765077883744266/1510000054507802785

Need to test that this didn't break anything.

[smj-edison]

Do you allow flags to be passed in after query parameters? I suppose this is more of an edge case, but -- might be needed in the future.

[osnr]

Generally, I think we allow flags anywhere? + it reads better this way, I think, without the letter right up next to paper

[osnr]

Yeah, I like the idea of eventually supporting --

[smj-edison]

Would you want a flag like -takefirst instead of try/on here?

[smj-edison]

Or I suppose this is just in case nothing is returned, never mind.

[s-ol]

Neat. /./ is a new bit of "syntax", right? I'm wondering if using uplevel to match When's binding logic could make sense:

AssignOne! the paper formats are /formats/
# equivalent to
set formats [QueryOne! the paper formats are /./]

# enables multiple capture (still enforcing single overall match)
AssignOne! the /medium/ formats are /formats/

You could also specify defaults inline, although that requires introducing specialized syntax once again:

AssignOne! the /medium=paper/ formats are /formats={letter a4}/