Restore Rust dual-artifact CLI bundling

[dmytrostruk]

Summary

• restore the real full Copilot CLI/Node SEA as the artifact returned by install_bundled_cli()
• keep install_bundled_runtime() and normal CliProgram::Resolve on the native copilot-runtime wrapper with adjacent runtime.node and required assets
• embed separate, independently checksummed CLI and runtime payloads instead of aliasing wrapper bytes under the copilot filename
• preserve bundled-in-process, no-default-feature extraction, build caches, custom extraction directories, and all eight supported platform variants
• invalidate the wrapper-as-CLI cache entry from the regression by checking the installed CLI against the embedded SEA size
• add regression coverage for distinct artifacts and the full CLI --binary-version contract

Fixes the Rust SDK regression introduced by #2463.

Validation

• cargo +nightly-2026-04-14 fmt --all -- --config-path .rustfmt.nightly.toml --check
• cargo clippy --all-targets --features test-support,bundled-in-process -- --no-deps -D warnings -D clippy::unwrap_used -D clippy::disallowed_macros -D clippy::await_holding_invalid_type
• cargo test --test cli_resolution_test — 7 passed
• cargo test --no-default-features --test cli_resolution_test — 8 passed
• cargo test --all-features --test cli_resolution_test — 7 passed
• generated and consumed both publish checksum snapshots, each containing all eight platform hashes

Size impact

For Copilot CLI 1.0.83-5 on Darwin ARM64:

• full CLI payload: 83,552,873 bytes
• filtered runtime payload: 40,925,644 bytes with default features, 72,594,661 bytes with bundled-in-process
• the restoration adds 83,552,873 bytes of compressed embedded payload; normal CliProgram::Resolve still extracts only the runtime bundle, while the SEA remains lazy behind install_bundled_cli()

[Copilot]

Copilot review overview

🔵 Needs a closer look

Cross-platform release packaging and extraction across eight artifact variants warrants final human validation.

Review tier: Balanced
Findings: None

What changed in this PR

Restores separate embedded CLI and runtime artifacts in the Rust SDK while preserving runtime resolution behavior.

Changes:

• Embeds and verifies distinct full-CLI and filtered runtime archives.
• Adds cache invalidation and cross-platform regression coverage.
• Updates platform snapshots and documentation.

File	Description
rust/​build/​in_process.rs	Builds and verifies separate CLI/runtime payloads.
rust/​src/​embeddedcli.rs	Extracts each payload through its appropriate installer.
rust/​src/​lib.rs	Clarifies public installer behavior.
rust/​tests/​cli_resolution_test.rs	Tests artifact separation and CLI version probing.
rust/​scripts/​snapshot-bundled-cli-version.sh	Adds musl release checksums.
rust/​README.md	Documents dual artifacts and eight platforms.

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[roji]

LGTM, fixes unintentional regression introduced in #2463.