fix: remove Git CLI dependency and hide Windows command windows

[wsp1911]

Summary

• Replace workspace-memory Git CLI calls with vendored libgit2.
• Preserve ignored ad-hoc notes in Phase 2 memory diffs.
• Prevent Windows console windows from flashing for MiniApp workers, native hooks, local workspace shell commands, and local Docker workspace processes.

Fixes #1749

Type and Areas

Type:

Bug fix / regression fix

Areas:

Rust core, services, agent runtime, desktop MiniApp runtime, Remote SSH

Motivation / Impact

Memory no longer requires a system Git installation to build workspace baselines or diffs. Ignored ad-hoc notes continue to participate in memory capture.

Windows release builds now create the affected background child processes with hidden console windows, including long-lived local Docker docker exec stdio sessions.

Verification

• pnpm run fmt:rs
• node --check src/apps/desktop/resources/worker_host.js
• cargo test -p bitfun-services-core --features workspace-runtime workspace
• cargo test -p bitfun-services-integrations --features remote-ssh-concrete (49 passed; 1 Docker-dependent test ignored)
• cargo check -p bitfun-services-integrations --features remote-ssh-concrete
• cargo check --workspace

Reviewer Notes

• The memory implementation uses vendored libgit2 and retains legacy diff rendering behavior.
• The ignored-note regression is covered by memory_workspace_diff_includes_ignored_ad_hoc_notes.
• No interactive verification was run. The Docker integration test remains opt-in via BITFUN_TEST_DOCKER_CONTAINER.

Checklist

• This PR is focused and does not include secrets, temporary prompts, generated scratch files, or unrelated artifacts.
• Relevant verification is recorded above.
• User-facing strings, docs, and locales are not affected.