fix: rename workspace runtime lock

[ovaso]

Summary

• Rename the hidden runtime workspace lock from .workspace.lock to .batchspace.lock.
• Retain the coordination file after each process exits; closing the file handle releases the OS lock, avoiding delete/recreate races.
• Add coverage for lock lifecycle and schedule contention; update English and Simplified Chinese docs, automation guidance, and changelogs.

Validation

• cargo fmt -- --check
• cargo test --locked
• cargo clippy --all-targets --all-features -- -D warnings
• cargo build --locked --release
• cargo test --locked --no-default-features
• cargo clippy --all-targets --no-default-features -- -D warnings
• cargo build --locked --release --no-default-features

Risk and rollback

Existing .workspace.lock files are no longer used. New invocations coordinate through .batchspace.lock; deleting either idle lock file is safe, but batch-git intentionally does not remove it automatically.

[chatgpt-codex-connector]

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