[deps] Upgrade core-ktx to 1.18.0, Chucker to 4.3.1 and Compose UI to 1.12.1

Summary

Upgrade the following dependencies in gradle/libs.versions.toml:

Dependency	Catalog key	Current	Target
`androidx.core:core-ktx`	`ktx`	1.17.0	1.18.0
`com.github.chuckerteam.chucker:library` (+ `library-no-op`)	`chucker`	4.3.0	4.3.1
Compose UI on Android	`composeBOM`	BOM 2026.08.00	1.12.1 via BOM 2026.09.00 (or via Compose Multiplatform)

core-ktx — used by app and app-tv.
Chucker — used by app, app-watch and library:designsystem. Bumping the shared chucker version ref updates both library and library-no-op.
Compose UI — Android modules currently get Compose from androidx.compose:compose-bom. Either:
- bump composeBOM to 2026.09.00, which maps Compose UI to 1.12.1, or
- get Compose UI 1.12.1 through Compose Multiplatform, if we move the Compose modules onto CMP as part of the KMP migration.
Check that material3 (pinned separately, 1.5.0-beta02) and the Wear/TV Compose artifacts still resolve and compile against the new Compose UI.

Versions updated in gradle/libs.versions.toml
./gradlew assemble passes (app, app-watch, app-tv)
./gradlew test, ./gradlew lintKotlin and ./gradlew detektAll pass
Quick smoke test of the Markets/Favorites/Detail screens and the Chucker notification in a debug build

Upgrade core-ktx to 1.18.0, Chucker to 4.3.1 and the Compose BOM to 2…