chore: update project structure and dependencies

[madisp]

Some spring cleaning. Adds CODEOWNERS, dependabot config, Gradle version catalogues, updates to the latest Gradle/JDK/AGP etc.

[Copilot]

Pull request overview

Updates the project’s build/dependency management and repo automation configuration, aiming to modernize Gradle/Android tooling and introduce maintenance automation.

Changes:

• Migrates Gradle plugin/dependency declarations to version catalogs (including a separate “fixed” catalog for intentionally pinned deps).
• Updates Gradle wrapper scripts/properties and adjusts module build configuration (compileSdk, Java toolchain).
• Adds repo automation/config (CODEOWNERS, Dependabot) and updates GitHub Actions workflows.

Reviewed changes

Copilot reviewed 14 out of 16 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
build.gradle.kts	Switches to plugin aliases from the libs version catalog.
settings.gradle.kts	Adds Foojay toolchain resolver plugin and defines the fixed version catalog.
gradle/libs.versions.toml	Introduces the main version catalog for plugins/libraries.
gradle/fixed.versions.toml	Adds a “fixed” catalog for dependencies intentionally kept at older versions.
test-runtime-android/build.gradle.kts	Uses catalog aliases, bumps compileSdk, and configures Java toolchain.
observer-interface/build.gradle.kts	Uses catalog aliases, bumps compileSdk, and configures Java toolchain.
gradle/wrapper/gradle-wrapper.properties	Updates the Gradle distribution URL.
gradle/wrapper/gradle-wrapper.jar	Updates the wrapper JAR to match wrapper changes.
gradlew	Updates POSIX wrapper script (notably -jar usage and template changes).
gradlew.bat	Updates Windows wrapper script (stderr output and -jar usage).
.github/workflows/build.yml	Updates CI actions versions and switches CI JDK version.
.github/workflows/deploy.yml	Updates deploy workflow actions versions and switches JDK version.
.github/dependabot.yml	Adds Dependabot configuration for GitHub Actions + Gradle.
.github/CODEOWNERS	Adds CODEOWNERS ownership mapping.
.tool-versions	Removes asdf tool version pinning.
mise.toml	Adds mise tool version pinning for Java.

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