Allow disabling individual keyboard controls with null (#333)

[CarlosNZ]

Closes #333.

What

Lets consumers disable any keyboardControls binding by setting it to null. A disabled binding is no longer intercepted, so the key falls through to its native browser behaviour. The motivating case is Tab: { tabForward: null, tabBack: null } turns off node-to-node Tab navigation so Tab/Shift-Tab resume normal focus traversal — useful for data sets where the built-in Tab behaviour isn't appropriate.

This supersedes the issue's "define a nonsense/unreachable key" hypothesis: that works by accident (a non-matching control never preventDefault()s) but is undiscoverable and doesn't read as intent. null states it in both the config and the types.

How

• eventMatch treats a null control as "never matches". Because handleKeyPress only calls preventDefault() on a match, a disabled key passes straight through to the browser.
• getFullKeyboardControlMap now distinguishes undefined (not supplied → keep default) from null (disable). The old truthy guard conflated them. The two modifier-array controls (clipboardModifier/collapseModifier) store [] when disabled, so their .includes() consumers stay null-safe and those fields remain real arrays.
• The generic-confirm fallback now checks === undefined, so an explicitly disabled per-type confirm (e.g. stringConfirm: null) isn't silently re-enabled.
• Types: every KeyboardControls field accepts | null; KeyboardControlsFull's KeyEvent-valued entries become KeyEvent | null.

Tests

• New unit tests in test/keyboard.test.ts: map behaviour (null KeyEvent → null, null modifier → [], disabled per-type confirm not re-enabled) and behavioural assertions on handleKeyPress (a disabled binding fires neither its action nor preventDefault; a default binding still does).
• Regression check: removing the eventMatch guard makes the suite fail to compile against the new KeyEvent | null type — the guard is load-bearing.
• Full suite green (496 passing), lint and pnpm compile clean.

Note

jsdom doesn't move focus on Tab, so the unit tests pin the contract we control (no preventDefault, no node-move). Native focus traversal after disabling is worth a quick manual confirm in a real browser.

Docs: README "Keyboard customisation" gains a bullet documenting the null disable. Changeset included (minor).

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Bundle size impact

json-edit-react

Format	Base raw	PR raw	Δ raw	Base gzip	PR gzip	Δ gzip
esm	56.43 KB	56.52 KB	🔺 +87 B (+0.15%)	20.12 KB	20.15 KB	🔺 +31 B (+0.15%)
cjs	57.93 KB	58.02 KB	🔺 +87 B (+0.15%)	20.21 KB	20.24 KB	🔺 +34 B (+0.16%)

_{Measured from build/index.{cjs,esm}.js. Gzip at level 9.}