feat(platform): add macOS support and fix cross-platform agent detection

[4nrry]

Why

The README already framed macOS and Windows as "supported secondary platforms via Tauri 2", but in practice:

• Agent detection didn't work on Windows. Rules match bare exe names (claude, node) and a Unix-only shell list, while sysinfo reports claude.exe/node.exe and Windows shells are cmd/powershell/pwsh. No agent would ever be detected.
• macOS had no packaging at all — Linux (.deb) and Windows (NSIS .exe) had build scripts + release workflows, but there was no .dmg script/workflow.
• CI only ran on Ubuntu, so cross-platform regressions were invisible.

What changed

Agent detection (opencherry_agents)

• Match exe basenames extension-insensitively so claude.exe / node.exe match rules written as claude / node.
• Recognize Windows shells (cmd, powershell, pwsh, wt, conhost, nu, …) in the require_shell_parent heuristic.
• Normalize path separators (\ → /) so exe_path_contains rules and the Antigravity exclusion work with Windows paths.
• Added unit tests for Windows exe names, Windows shells, and Windows shell-parent matching.

Packaging & CI

• scripts/build-macos.sh — produces an unsigned .dmg (optional cross-arch via OPENCHERRY_MAC_TARGET).
• .github/workflows/release-macos.yml — builds Apple Silicon (aarch64) + Intel (x86_64) .dmg images, attaching to v* releases or uploading as artifacts on workflow_dispatch.
• .github/workflows/ci.yml — new cross-platform matrix running the library-crate tests on windows-latest and macos-latest.
• tauri.conf.json — macOS minimumSystemVersion (10.15) and NSIS currentUser install mode (no admin prompt for an unsigned dev tool).
• justfile — build-macos / build-windows recipes.

Docs

• README: macOS .dmg install section + per-platform dependency notes.
• AGENTS.md: updated CI/release workflow expectations.

Testing

• cargo fmt --all -- --check ✅
• cargo clippy -p opencherry_core -p opencherry_repo -p opencherry_agents -p opencherry_persistence --all-targets -- -D warnings ✅
• cargo test on all four library crates ✅ (42 tests, including the new Windows-detection tests)
• bash -n scripts/build-macos.sh ✅
• Not run locally: full tauri build for .dmg/.exe (needs macOS/Windows hosts — that's what the release workflows are for) and the Linux desktop E2E (no WebKitWebDriver in this environment).

🤖 Generated with Claude Code

https://claude.ai/code/session_014PZXacyXbTKeZEn9uXoPWM

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Generated by Claude Code

[4nrry]

Revisado! Testei localmente e os builds/testes no backend (Rust) e frontend (SolidJS) passaram com sucesso. O código para o suporte ao macOS parece ótimo.