Adopt ui-core's localization system

[humanapp]

Adopt the ui-core localization runtime

Routes every user-visible string and every default font choice in the library
through ui-core's loc runtime, and ships translation catalogs for the
library's own captions. English rendering is bit-identical: with no
translation table assigned, ui.locFont() returns the same bitmaps.font8
object the removed constants held, so the renderer receives the identical
font object it always did.

What changed

• Captions: the entry-widget key captions now resolve at render time via
  loc(...): text entry's abc, ABC, OK, 123, #+=, space and
  numeric entry's +/-, DEL, OK. Glyph-like captions (<-, digits,
  .) stay literal.
• Default fonts: the module-level font constants (BUTTON_DEFAULT_FONT,
  LABEL_DEFAULT_FONT, NUMERIC_ENTRY_FONT, TEXT_ENTRY_FONT) are removed;
  every use site resolves style.font || locFont() at render/measure time.
  Two module-level text-entry styles and the constructor styles no longer
  bake a font field (a comment explains the constraint: a module-scope
  capture would run before the app assigns a per-language font). Per-control
  font overrides still win.
• Measurement: width math now uses the font that actually renders.
  UiLabel measures with its own resolved font; the picker title draw
  passes an explicit font: locFont() (previously font-less auto-select)
  and both title/choice width calculations use locFont().charWidth instead
  of hardcoded bitmaps.font8.charWidth.
• Tests: runLocalizationSmokeTest() renders a real UiTextEntryModal
  and asserts drawn captions flip from OK/space to table-supplied values
  and back, and that label measurement follows an assigned default font and
  reverts to font8 metrics when cleared.
• Catalogs: locales/en.json (generated, 8 keys), 19 language catalogs
  for the captions, and locales/README.md documenting the catalog rules,
  the key-cap length constraint, and the caption workflow. Apps can override
  any library translation because app catalog layers win at merge.
• Tooling: scripts/locstrings.mjs (shared extractor) and
  npm run loc:strings.

Verification

• mkc build green, including test files; assertions executed in the
  simulator.
• English font resolution audited site-by-site: every draw/measure path
  resolves to the identical bitmaps.font8 object as before this change.
• Localized captions exercised on hardware via downstream microcode-v2
  language builds (fr, pl, es-ES).

Release note

Parked as draft until ui-core bump, pending microbit-apps/ui-core#1

[Copilot]

Pull request overview

Adopts the ui-core localization runtime across ui-controls so that user-visible captions and default fonts are resolved through loc(...) / locFont() at render/measure time, and ships locale catalogs plus extraction tooling to maintain them.

Changes:

• Localizes text-entry and numeric-entry key captions via loc(...) and routes relevant draw paths through locFont().
• Updates measurement logic (e.g., picker title/choices) to use the active localized default font metrics rather than hardcoded font8 metrics.
• Adds locale catalogs + documentation and introduces a loc:strings script to regenerate locales/en.json, plus a localization smoke test.

Reviewed changes

Copilot reviewed 30 out of 30 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
text-entry.ts	Localizes key captions and switches rendering to locFont(); removes module-scope font capture from key styles.
numeric-entry.ts	Localizes key captions and switches rendering to locFont().
modal-grid.ts	Uses locFont() for picker title rendering and width calculations.
label.ts	Updates label default font selection to use locFont() instead of a module constant.
test.ts	Adds a localization smoke test covering caption substitution and default-font-driven measurement.
scripts/locstrings.mjs	Adds extractor to regenerate locales/en.json from loc* callsites in source files.
scripts/sync-local-pxt-deps.js	Adds helper script for syncing local PXT dependency cache blobs.
package.json	Adds npm run loc:strings script entry.
locales/README.md	Documents catalog rules and workflow (including key-cap length constraint).
locales/en.json	Adds generated English catalog for library captions.
locales/ca.json	Adds Catalan caption catalog.
locales/cs.json	Adds Czech caption catalog.
locales/cy.json	Adds Welsh caption catalog.
locales/de.json	Adds German caption catalog.
locales/es-ES.json	Adds Spanish (Spain) caption catalog.
locales/es-MX.json	Adds Spanish (Mexico) caption catalog.
locales/eu.json	Adds Basque caption catalog.
locales/fil.json	Adds Filipino caption catalog.
locales/fr.json	Adds French caption catalog.
locales/fr-CA.json	Adds French (Canada) caption catalog.
locales/hr.json	Adds Croatian caption catalog.
locales/hu.json	Adds Hungarian caption catalog.
locales/it.json	Adds Italian caption catalog.
locales/nl.json	Adds Dutch caption catalog.
locales/pl.json	Adds Polish caption catalog.
locales/pt-BR.json	Adds Portuguese (Brazil) caption catalog.
locales/pt-PT.json	Adds Portuguese (Portugal) caption catalog.
locales/ru.json	Adds Russian caption catalog.
locales/tr.json	Adds Turkish caption catalog.

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[thomasjball]

looks good to me!