docs(dev_board): add "contest-adapted boards" table to Development_Board

[tanghao-xiaomi]

What

Add a new "Contest-adapted boards" table at the end of zh-cn/dev_board/Development_Board.md, covering boards that were adapted during the 2026 openvela AI Hardware Developer Contest but were not yet listed in the general development-board catalog.

Boards added (7)

Board	Chip
SF32LB52-DevKit-LCD	SiFli SF32LB52
100ASK DShanPixVela-Devkit	Allwinner R528
BES2800BP EVB	BES2800BP
NUCLEO-H7A3ZI-Q	STM32H7A3ZI
GD32F470V-START	GD32F470V (GD32F4 series)
D12x series EVM	ArtInChip D12x (RISC-V)
D13x series EVM	ArtInChip D13x (RISC-V)

Each adaptation case links to the board-level README on the corresponding vendor repo's dev-ai-contest-2026 branch.

Principles

• No duplication: ESP32-S3-EYE, LCKFB Huangshan Pi, and STM32H750B-DK are already listed in the general catalog table above; the new table only references them instead of repeating.
• Certified board untouched: Gemini-S1 already lives on the Certified Boards page and is left as is.
• Column layout matches the existing catalog table (vendor / model / chip / adaptation case / use cases / purchase / support).

To be completed

• D13x adaptation case is marked "TBD" (consistent with the Supported Hardware page, pending a dedicated D13x README).
• Some purchase / support cells are temporarily set to "contact vendor / distributor" due to the lack of reliable public links; to be filled in later.

Changes

• 1 file changed (Development_Board.md)
• Source: the "supported boards" list in zh-cn/contest_2026/hardware_porting/supported_hardware.md