chore: validate MoonBit 0.10.11 compatibility

[brickfrog]

Changes

• Pin the CI and Copilot installer to MoonBit 0.10.11+6ff76a5f9.
• Verify the toolchain and core archives with their SHA-256 digests.
• Apply the formatting from MoonBit 0.10.11.

Verification

• The isolated installer accepted both archive checksums.
• moon version --all --json reported moonc v0.10.11+6ff76a5f9 and moon/moonrun 0.1.20260827.
• moon check --deny-warn passed for native, JavaScript, and wasm-gc.
• Tests passed: native 293, JavaScript 280, and wasm-gc 265.
• Native release tests passed: 293. The native release build passed.
• Native file-subscriber tests passed: 9. Native HTTP transport tests passed: 4.
• Native async-cancellation tests passed: 4. Scoped-state tests passed: 3.
• The command smoke test produced the required eight ordered records on native, JavaScript, and wasm-gc.
• moon info produced no interface change. moon fmt --check passed.

Release decision

No release. This pull request changes the CI pin and formatting only. It does not change the public API or runtime behavior.