[pull] main from Comcast:main - #232

* oxlint: add unicorn rules

* oxlint: curate unicorn rules

Go through every unicorn rule, disable the ones that do not fit this
codebase, tune the options of the ones that do, and fix the code they flag.

Disabled:
- `no-null`, `no-useless-undefined`: `null`/`undefined` literals are required
  by the public `Maybe<T>` API, by React (`useRef<T>(undefined)`,
  `renderCell: () => null`) and by `noImplicitReturns`
- `prefer-number-coercion`: rewrites `parseFloat('10px')` to `Number('10px')`
- `prefer-at`: `at(-1)` returns `T | undefined` and is suggested for DOM
  collections, which have no `at()`
- `no-nested-ternary`, `empty-brace-spaces`, `number-literal-case`: oxfmt
  already owns this
- `prefer-includes`, `no-instanceof-array`: duplicate reports
- `no-negated-condition`, `prefer-query-selector`: style

Tuned:
- `filename-case`: camelCase + PascalCase
- `switch-case-braces`: `avoid`
- `prefer-ternary`: `only-single-line`
- `no-array-sort`: `allowAfterSpread`
- `max-nested-calls`: `max: 4`

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01BHDtvyEwsiM6EQJsgdiHt9

* website: use `Array.from(value, mapFn)` instead of `[...value].map(mapFn)`

Avoids building an intermediate array.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01BHDtvyEwsiM6EQJsgdiHt9

* Extract `getRowTracks` in `useViewportRows`

Both call sites built the same `repeat(n, Xpx)`/`Xpx` string. Extracting it
removes the duplication and keeps each `gridTemplateRows` append on one line.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01BHDtvyEwsiM6EQJsgdiHt9

* Avoid `Array#entries` allocation in `useCalculatedColumns`

`entries()` allocates a `[index, value]` tuple per column. Use an indexed
loop instead, matching the other loops in this file.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01BHDtvyEwsiM6EQJsgdiHt9

* Avoid allocating a key list per group in `TreeDataGrid`

`expandGroup` re-runs on every expand/collapse and only needed `Object.keys`
for `setSize`. Store `setSize` on each group entry instead — it is already
known while grouping, in a memo that recomputes far less often — so
`expandGroup` can walk the dictionary with `for…in` and no keys array.

`groupRows` now uses `Object.keys` + lookup instead of `Object.entries`,
which drops one tuple per group.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01BHDtvyEwsiM6EQJsgdiHt9

* website exports: use iterators

* review

* review

* review

* dict -> map

---------

Co-authored-by: Claude Opus 5 (1M context) <[email protected]>