Add KanuniLabs DataGrid and KanuniLabs PivotGrid

[kanunilabs-dev]

Two closed-source commercial libraries with a free tier.

githubRepo is null for both, following the flexmonster and spreadjs entries,
since the source is not public.

Several feature flags are strings rather than booleans because the capability
is split across the free and paid tiers, and a bare true/false would overstate
one or the other. For example rowGrouping on the data grid: single level is
free, multi-level is paid.

responsive is a string for the same reason. Measured at 375px: the page does
not overflow and the grid scrolls horizontally, but there are no mobile
breakpoints and most toolbar controls are under 40px, so "works well on mobile"
would be a stretch.

Note: npx awesome-lint fails on my Windows checkout with "Invalid GitHub repo
URL" — it does the same on a clean, unmodified clone, so it looks unrelated to
this change. Relying on CI for the README check.

[kanunilabs-dev]

Correction to my note above: I said I'd rely on CI for the README check, but
there is no PR workflow here — the only workflow is the weekly rebuild, on a
cron trigger.

I looked into the lint failure properly. npx awesome-lint fails because
package.json has no repository field, so the linter cannot resolve the repo
URL and remark-lint:awesome-github reports "Awesome list must reside in a valid
git repository". It fails the same way on a clean checkout of main with no
changes, so it is not specific to this branch or to Windows.

I checked the README rules by hand against contributing.md instead: dash
separator, description starts with a capital and ends with a period, and the
entries are in alphabetical order.