chore: update kotlin and compose bom

[ovitrif]

Parent: #1113
Blocks: #1114

Goal

Move Kotlin and Compose to the latest mutually compatible stable release set available when implementation begins on the current AGP 8.13.2 baseline. Establish the Kotlin 2.3.21 or newer baseline consumed by #1114, then create two focused follow-up issues that align repository guidance and source style with the selected language capabilities.

Deliverables

• Research the compatibility matrix across current AGP 8.13.2, planned AGP 9.3.0, Kotlin, Compose compiler plugin, Kotlin serialization plugin, Kotlin BOM, Compose BOM, KSP 2.3.10, Hilt 2.60.1, and the supported Android Studio version.
• Select Kotlin 2.3.21 or newer and a mutually compatible stable Compose set; AGP 8.13.2 is the supported current baseline for Kotlin 2.3.
• Update the shared Kotlin version used by the Compose compiler and serialization plugins.
• Update the Kotlin BOM and Compose BOM.
• Apply required source, compiler-option, Compose API, test, lint, and stability-annotation changes.
• Confirm the selected Compose configuration is stable by default and remove redundant project configuration.
• Record the selected version matrix and primary-source compatibility evidence in the PR.
• Keep catalog ownership clear: this issue owns Kotlin and Compose versions; chore: upgrade to agp 9 and configure parallelism #1114 consumes their landed state, and the catalog-wide dependency issue audits the final combined state.

Required follow-up issue A

Title: docs: align kotlin and compose agent rules

• Review the selected Kotlin and Compose release notes and identify rules that describe superseded language, compiler, Compose stability, or API patterns.
• Update canonical AGENTS.md and focused .ai/rules/ documents after the shared instruction consolidation lands.
• Express current preferred patterns with concise repository examples and direct verification commands.
• Remove guidance absorbed by current language/compiler defaults.
• Keep this issue specific to Kotlin/Compose version-dependent guidance.

Acceptance:

• Repository guidance matches the selected versions.
• Searches find no superseded Kotlin or Compose recommendation.
• Every added rule points to a current repository example or primary source.
• Policy is not duplicated across AGENTS.md and .ai/rules/.

Required follow-up issue B

Title: refactor: adopt current kotlin language features

• Inventory repeated code-style patterns that the selected Kotlin version can replace with clearer current language features.
• Define one mechanical migration family per PR.
• Prioritize patterns with unit, Compose, or instrumentation coverage.
• Update detekt only where a selected current-language pattern requires it.
• Preserve architecture and product behavior.
• Record pattern families, affected packages, automated rewrite boundaries, and verification routes before implementation.

Acceptance:

• The issue names each migration and exact source surface.
• Each PR covers one mechanical concern.
• Baseline and post-refactor tests prove unchanged behavior.
• Compile, unit, lint, and relevant device/journey checks pass per slice.

Acceptance criteria

• The catalog uses Kotlin 2.3.21 or newer with one mutually compatible stable Compose release set on AGP 8.13.2.
• The selected set satisfies the published compatibility requirements for chore: upgrade to agp 9 and configure parallelism #1114's AGP 9.3.0, KSP 2.3.10, and Hilt 2.60.1 matrix.
• Compose compiler and serialization plugin versions align with Kotlin.
• Kotlin BOM and Compose BOM resolve without conflicts or forced downgrades.
• The dependency report has one effective Kotlin standard-library line and one coherent Compose set.
• Source and tests compile without deprecated compiler flags introduced by the upgrade.
• Stability reports and recomposition-sensitive UI tests confirm intended stable-by-default behavior.
• just compile, just test, just lint, just build, and just test android pass.
• Representative Compose UI and E2E journeys pass.
• Android Studio sync and previews work on the supported IDE.
• The two follow-up issues above are created and linked before this issue closes.

References

• AGP requirements for Kotlin versions
• AGP 9 compatibility findings on #1114