feat: configure proxy and observer rendering

[SirEdvin]

Summary

• add persisted target text and box styles to Peripheral Proxy and Remote Observer
• add shared configurator screen, validated serverbound updates, Lua setters, and configurable overlay rendering
• reuse shared style controls/render primitives across Network Manager, Proxy, and Observer
• add OpenSpec artifacts, localization, TypeScript fixtures, and server/client GameTests

Testing

• ./gradlew :typescript-tests:compileTestLua --no-daemon
• timeout --foreground 20m xvfb-run -a ./gradlew clientGameTest --no-daemon -PminimalTestEnvironment
• timeout --foreground 20m xvfb-run -a ./gradlew gameTest --no-daemon -PminimalTestEnvironment
• timeout --foreground 10m ./gradlew build --no-daemon
• openspec validate add-proxy-observer-render-settings --json