ch32v: deploy is unimplemented while board JSONs advertise wch-link/minichlink/isp/wlink and docs say Supported

[zackees]

Part of the CH32V pipeline audit (#1102).

What happens

The daemon's deploy dispatch has no CH32V arm — Platform::Ch32v falls into the catch-all in crates/fbuild-daemon/src/handlers/operations/deploy.rs (~line 805):

_ => {
    return Err(FbuildError::DeployFailed(format!(
        "deployer for {:?} not yet implemented", platform)));
}

Meanwhile every one of the 17 CH32V board JSONs advertises a full upload story:

"upload": { "protocol": "wch-link", "protocols": ["wch-link", "minichlink", "isp", "wlink"] }

and docs/BOARD_STATUS.md lists "CH32V (RISC-V) Platform - Supported". So a user who builds successfully and runs fbuild deploy tests/platform/ch32v003 -e ch32v003 gets a hard failure after the daemon has already preempted the chosen serial port (preemption is correctly released in the error path, but the UX is: everything claims deploy works until the last step).

Supporting gaps

• No WCH-Link probe recognition anywhere in the deploy/serial stack. crates/fbuild-serial/src/boards.rs (~line 602) classifies every 0x1A86 (WCH/QinHeng) device as Esp32ExternalUart via a VID wildcard — a WCH-Link (RV mode 1a86:8010, DAP mode 1a86:8012) or a CH32V's native CDC gets labeled as an "ESP32 external UART bridge".
• Per the repo rule, WCH-Link VID/PID identity must come from the FastLED/boards registry (the vid-ingest: WCH / QinHeng (0x1A86 — CH32V/X + CH340 bridges) #730 vid-ingest already covered 0x1A86 families — verify the probe entries are present there rather than hardcoding).

Suggested direction

Same shape as the LPC probe-rs path (crates/fbuild-deploy/src/probe_rs.rs): a pinned, checksummed wlink (or minichlink) binary managed under ~/.fbuild/{prod|dev}/tools/, a Ch32vDeployer implementing the Deployer trait, dispatch keyed off board.upload.protocol, and WCH-Link presence detection via FastLED/boards profiles. Until that lands, at minimum the error message should say "CH32V flashing is not implemented yet — use wlink/minichlink manually" instead of the generic not yet implemented, and BOARD_STATUS should say build-only.

Severity: HIGH (advertised user-facing capability is absent).