refactor(process): add bounded blocking execution

[lamalex]

Adds bounded blocking process execution to moon_process.

VCS plugins invoke executables through synchronous extism host functions. Centralizing this behavior in moon_process avoids embedding generic subprocess infrastructure in the plugin host, and enables sharing some of moon's existing sub process code.

[Copilot]

Pull request overview

Adds a blocking (synchronous) process execution path to moon_process intended for environments that can’t use async execution (like synchronous Extism host calls), while still supporting bounded execution via timeouts and output limits.

Changes:

• Introduces a new blocking capture executor (CaptureOptions, blocking capture methods, and process-group/job-object cleanup) in crates/process/src/blocking.rs.
• Adds new ProcessError variants for output limits and timeouts to surface bounded-execution failures.
• Expands test coverage for blocking capture behavior (timeouts, output limits, byte-preserving output, and descendant cleanup).

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
crates/process/tests/exec_command_test.rs	Adds unit tests covering blocking capture behavior, bounds enforcement, and descendant cleanup.
crates/process/src/shared_child.rs	Exposes convert_exit_status internally for reuse by the blocking executor.
crates/process/src/process_error.rs	Adds OutputLimitExceeded and Timeout error variants (with diagnostics).
crates/process/src/lib.rs	Wires in the new blocking module and re-exports its public API.
crates/process/src/exec_command.rs	Exposes internal helpers (create_sync_command, handle_nonzero_status) for blocking executor reuse.
crates/process/src/blocking.rs	New blocking capture implementation with timeout/output-limit enforcement and process-tree cleanup.
crates/process/Cargo.toml	Updates Windows windows-sys features to support job objects used for cleanup on Windows.

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[codspeed-hq]

Merging this PR will improve performance by 43.81%

⚠️ Unknown Walltime execution environment detected

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For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

⚡ 1 improved benchmark
✅ 22 untouched benchmarks

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	WallTime	hash_files[1000]	17.5 ms	12.1 ms	+43.81%

Tip

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_{Comparing lamalex:vcs/process-refactor (556463a) with master (c3de6c9)}

[lamalex]

Setting to draft while command changes are being extracted to starbase