Definition factories: guard-preserving customization of pre-built components (#350)

[CarlosNZ]

Implements the core of #350: the pre-built custom-node definitions in @json-edit-react/components are now exported as definition factories rather than plain objects, so customizing them can no longer silently drop the built-in safety condition.

What changed

• createDefinitionFactory (package-private, _common/): takes a plain CustomNodeDefinition base — its condition interpreted as the guard — and returns the consumer-facing factory. Consumer condition overrides are targeting, ANDed with the guard; the explicit guard key replaces the guard; componentProps shallow-merges; everything else is override-wins. The base objects keep their names/shape but are no longer exported — the factory is the only door.
• 12 factories replace the former object exports: hyperlinkDefinition(), enhancedLinkDefinition(), datePickerDefinition(), dateObjectDefinition(), colorPickerDefinition(), markdownDefinition(), imageDefinition(), booleanToggleDefinition(), bigIntDefinition(), nanDefinition(), symbolDefinition(), undefinedDefinition(). Calling with no arguments reproduces the previous definition exactly.
• Components + props types exported alongside the factories (MarkdownComponent, DateTimePicker, …) for wrapping and hand-rolled definitions; DefinitionOverrides<T> exported as the override-surface type. CodeEditor / ReactSelect stay component-only (no factory is possible — they have no default condition).
• Demo converted — the former spread-usages were live examples of the footgun (both manually re-added typeof value === 'string' to compensate for dropping the guard); they're now factory calls with that boilerplate gone. Also removed a stale "override by index" comment (getConditionalDefinitions matches by name).
• Docs: migration guide §2 (v1 LinkCustomNodeDefinition users now land on hyperlinkDefinition()), README spot-fixes (the components README usage example referenced a DateTimePickerDefinition export that never existed), two existing changesets corrected, new changeset added.
• Cleanup: BooleanToggle's inline props generic ({ linkStyles?, stringTruncateLength? }, copy-pasted from Hyperlink) dropped — the component takes no custom props.

Verification

• pnpm compile (components) and demo tsc -b --force both clean
• Full rollup build: flattened build/index.d.ts exports exactly the designed surface — factories + components + props types + DefinitionOverrides; no createDefinitionFactory, no raw definition objects
• Whole-tree sweep for the 13 old export names: remaining references are only the internal consts, the frozen demo/src/v1, and deliberate v1-name mentions in migration contexts

Follow-ups (tracked in #350)

• Components README documentation: usage tiers, guard escape hatch, "UI-replacement components" category for CodeEditor/ReactSelect
• Unit tests for the factory merge policy — needs a test-infrastructure decision first (the package has no Jest setup; core's config excludes packages/)

🤖 Generated with Claude Code

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Bundle size impact

@json-edit-react/components

Format	Base raw	PR raw	Δ raw	Base gzip	PR gzip	Δ gzip
esm	12.66 KB	13.22 KB	🔺 +572 B (+4.41%)	4.26 KB	4.49 KB	🔺 +242 B (+5.55%)
cjs	13.30 KB	13.91 KB	🔺 +626 B (+4.60%)	4.14 KB	4.36 KB	🔺 +228 B (+5.38%)

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