docs: polish README for accuracy and clarity

[Merkost]

Summary

Builds on #9. The README documented an API surface that has drifted from the code, so this corrects the inaccuracies and tightens the prose. Verified every signature against the source before editing.

Accuracy fixes

• Instance API throughout — the examples used CurrencyFormatter.format*(...) as static calls, but CurrencyFormatter is a locale-bound class; only getFractionDigits / getFractionDigitsOrDefault are on the companion.
• Currency → Kurrency — there is no public Currency type, no Currency(code, fractionDigits) constructor, and no fromCode(code, locale) overload. Documented Kurrency.fromCode + predefined constants.
• Compose locale interop — it's KurrencyLocale.fromComposeLocale(locale), not locale.toKurrencyLocale().
• CurrencyFormat interface — corrected to the real members (String-returning format* methods + getFractionDigitsOrDefault).
• Versions — artifacts 0.2.3 → 0.3.1; Kotlin badge 2.2.0 → 2.4.0.

Polish

• Removed redundant inline comments and changelog-style wording.
• Replaced bullet lists with tables for errors and platform support.
• Light restructuring for flow; section set and TOC unchanged.

No code changes.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR updates the project documentation to better reflect the current public API, but it also includes several non-doc changes: formatter behavior adjustments, Android currency validation changes, build configuration updates, and test suite restructuring/expansion.

Changes:

• Refined README.md to match the current API surface (instance-based formatting, Kurrency type, Compose interop, updated versions).
• Adjusted formatter implementations (notably JVM fraction-digit handling; Android currency code normalization/validation logic).
• Reworked/added tests (new common regression test, new Android device tests, removed older Android instrumented test) and updated build tooling/versions.

Reviewed changes

Copilot reviewed 13 out of 19 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
sample/shared/src/commonMain/kotlin/org/kimplify/kurrency/sample/KurrencySample.kt	Updates import to compose.rememberCurrencyState after package/API organization changes.
sample/shared/src/commonMain/kotlin/org/kimplify/kurrency/sample/CurrencyListScreen.kt	Updates import to compose.rememberCurrencyState for consistency with compose package.
README.md	Large doc refresh to align examples and API reference with current code and versions.
kurrency-core/src/jvmMain/kotlin/org/kimplify/kurrency/CurrencyFormatterImpl.kt	Ensures JVM currency formatting uses the currency’s own fraction digits.
kurrency-core/src/commonTest/kotlin/org/kimplify/kurrency/JpyFractionDigitsTest.kt	Adds regression coverage for JPY having 0 fraction digits outside JP locale.
kurrency-core/src/androidTest/kotlin/org/kimplify/kurrency/CurrencyStateTestInstrumented.kt	Removes prior Android instrumented tests for CurrencyState.
kurrency-core/src/androidMain/kotlin/org/kimplify/kurrency/CurrencyFormatterImpl.kt	Switches Android formatting/validation pieces toward ICU types and adds cached validity check.
kurrency-core/src/androidDeviceTest/kotlin/org/kimplify/kurrency/LocaleFormattingTestInstrumented.kt	Adds device-level locale formatting tests (symbol/ISO/fraction digits).
kurrency-core/src/androidDeviceTest/kotlin/org/kimplify/kurrency/KurrencyLocaleTestInstrumented.kt	Adds device tests for locale parsing/system/predefined constants.
kurrency-core/src/androidDeviceTest/kotlin/org/kimplify/kurrency/KurrencyErrorTestInstrumented.kt	Adds device tests for KurrencyError behavior and messages.
kurrency-core/src/androidDeviceTest/kotlin/org/kimplify/kurrency/JpyFractionDigitsTestInstrumented.kt	Adds Android device regression test for JPY decimals.
kurrency-core/src/androidDeviceTest/kotlin/org/kimplify/kurrency/CurrencyTestInstrumented.kt	Adds broader Android device tests for Kurrency formatting/validation edge cases.
kurrency-core/src/androidDeviceTest/kotlin/org/kimplify/kurrency/CurrencyMetadataTestInstrumented.kt	Adds Android device tests for CurrencyMetadata.
kurrency-core/build.gradle.kts	Updates KMP/Android and JS target configuration and test source set dependency wiring.
kurrency-compose/src/commonTest/kotlin/org/kimplify/kurrency/compose/CurrencyStateTest.kt	Fixes test package to org.kimplify.kurrency.compose and updates imports accordingly.
kurrency-compose/src/commonMain/kotlin/org/kimplify/kurrency/compose/CurrencyState.kt	Moves CurrencyState into the compose package and removes debug logging lines.
kotlin-js-store/yarn.lock	Updates JS dependency lockfile (large dependency churn).
gradle/wrapper/gradle-wrapper.properties	Updates Gradle wrapper version.
gradle/libs.versions.toml	Updates Kotlin/AGP/Compose and other dependency versions; bumps SDK targets.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.