[LeenHawk]

OpenHarmony builds currently overwrite DEVECO_SDK_HOME by walking three parents from OHOS_HOME. With Huawei's command-line SDK layout (sdk/default/openharmony), this selects the parent of sdk; it also discards a caller's explicit SDK root.

Preserve an explicitly configured DEVECO_SDK_HOME and infer the SDK root for both sdk/default/openharmony and sdk/default/openharmony/<api> layouts. Resolve it during environment initialization and report an error for a path too shallow to infer, instead of panicking during command construction.

Validation: cargo check --lib --offline, rustfmt, and git diff --check passed.

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[LeenHawk]

Could a maintainer review this SDK-root fix and consider merging it into feat/ohos? The current diff is limited to src/open_harmony/env.rs: it preserves an explicit SDK root and supports both versioned and unversioned SDK layouts. The host compile and formatting checks are recorded in the description, and the reported security checks passed. Happy to address any feedback. Thank you!