feat(render): Add RGB565 raster path and ESP32-P4 PPA backend

[HalfSweet]

Summary

• add opaque PSP PSM5650 texture support and a native RGB565 raster target
• add an ESP32-P4 DrawList backend backed by PPA FILL, A8 BLEND, and SRM
• preserve DrawList ordering with an RGB565 software fallback for unsupported operations
• add a reusable ESP-IDF adapter, component smoke application, documentation, and CI
• keep the complete rendering path in RGB565 without a full-frame RGB888 or ARGB8888 intermediate

Implementation

The new pocketjs-esp32p4-ppa backend interprets DrawLists directly into an RGB565 destination.

Hardware-compatible operations are routed to:

• PPA FILL for opaque rectangles
• PPA BLEND for translucent rectangles, antialiased glyphs, and white-alpha textures
• PPA SRM for compatible opaque PSM5650 textures, including exact scaling, quarter-turn rotation, and mirroring

Unsupported gradients, triangles, texture formats, transforms, and sampling cases fall back to the native RGB565 software rasterizer in DrawList order.

The reusable ESP-IDF adapter:

• registers separate FILL, BLEND, and SRM clients
• uses blocking transactions so subsequent PPA and CPU operations observe completed pixels
• expands RGB565 FILL colors through fill_argb_color
• rejects overlapping SRM input/output buffers
• accepts only scale factors represented exactly in the PPA's 1/16 increments
• leaves display initialization, presentation buffers, and panel-specific behavior in the product BSP

Linear alpha-texture classification and edge sampling are shared with the core rasterizer. Colored transparent textures using linear filtering correctly fall back to software rendering.

Compatibility

• ESP-IDF release/v6.0: supported and used as the CI baseline
• ESP-IDF release/v6.1: supported and locally build-tested
• versions older than v6.0 have not been tested
• target: ESP32-P4

Hardware status

In the M5Stack Tab5 hardware integration build, the average frame rate reached 19.8 FPS during extended operation. The test was conducted at a CPU frequency of 360 MHz and a resolution of 1280 × 720.