Modernize and Unify Golden Tiles Architecture and Visuals

## Context
As part of the modernization of the `WearTilesKotlin` module, the main `MessagingTileService` was migrated to the stable 1.4/1.6 releases and unified under the `Material3TileService` architecture.

To keep the initial migration PR https://github.com/android/wear-os-samples/pull/1367 focused and to simplify the review process, the reference layouts in `com.example.wear.tiles.golden` (debug source set) were intentionally left in their current state. While they remain fully functional and correctly render with Material 3 Dynamic Colors on API 36+ devices, they still utilize a custom `BaseTileService` wrapper and older static preview assets.

This issue tracks the planned follow-up to unify these reference implementations with the rest of the module's architecture.

## Planned Work
1. **Refactor Architecture:**
* Migrate all Golden Tile implementations (Alarm, Calendar, Goal, etc.) from the custom `BaseTileService` to extend `Material3TileService` natively.
* Unify resource management and request logic with the modern `tileResponse` pattern used in the main sample.
* Remove the now-redundant `BaseTileService.kt`.

2. **Refresh Visual Assets:**
* Regenerate the static preview PNGs (`tile_preview_*.png`) from an API 36 emulator to reflect the current Material 3 dynamic look.
* Update the `golden_tiles.png` master screenshot in the `README.md`.

## Goal
The final outcome will be a cohesive module where all Tiles—both main and reference—follow a single architectural pattern, providing a consistent and modern learning resource for developers.