v0.3.0

feat: update stable-diffusion.cpp to master-982-0518b34 (#27)

* chore: prepare upstream 982 qualification with ABI evidence

* fix: run CFG unbatched in Metal builds and record upstream 982 evidence

Upstream 982 enables batched CFG by default, and ggml-metal GROUP_NORM
writes only the first batch item (leejet/stable-diffusion.cpp#2149), so a
batched step returns a wrong image as success. sd_dart_new_sd_ctx loads a
copy with batched_cfg off when the library is built with Metal.

Smoke-tests conversion under a non-ASCII UTF-8 path on every target, and
records the Metal controls, local suite and remaining gates.

* fix: document auto attention modes and check the Metal guard wiring

A null flash_attn_mode or conv_direct_mode with its legacy flag false
selects upstream's auto probes, which change output and are not
seed-reproducible on Metal. Record the explicit consumer mapping that
keeps v0.2.0-4 behavior.

build.py now fails after configure when stable-diffusion lacks the
SD_DART_METAL or SD_DART_GPU_BACKEND value its target needs, and the CI
build jobs run the runtime API test against the built runtime instead of
skipping it.

* docs: list the carried pickle patch beside the Metal CFG guard