feat(cli): make bitfun the cross-platform primary command

[limityan]

Summary

• make bitfun the primary CLI command while keeping the Cargo package/crate name bitfun-cli
• retain bitfun-cli as a thin deprecated compatibility launcher with an exact stderr warning, argument/exit forwarding, signal-safe handoff, and an actionable incomplete-installation error
• provide paired, transactional installers and release archives for Windows, macOS, and Linux, including rollback checks and current-shell/PATH guidance
• publish Windows x64 ZIP artifacts with static CRT linkage and reject unexpected Visual C++ Redistributable dependencies during packaging
• keep the five-platform native build/install/rollback/package matrix in release and explicit manual workflows, not ordinary pull-request CI

Compatibility and scope

• existing service identifiers, data/log paths, Cargo commands, and archive naming remain bitfun-cli; only the user-facing primary executable changes
• official installers and archives always ship bitfun and deprecated bitfun-cli as a pair; selectively installing only the compatibility launcher is unsupported and reports recovery guidance
• Windows foreground CLI behavior is fully supported; daemon auto-start remains unchanged and is not expanded by this PR
• Homebrew integration is a post-publication asynchronous notification. A successful repository dispatch only proves GitHub accepted the notification; the external tap owns formula rollout and readback for both entrypoints

Validation

• cargo test -p bitfun-cli
• cargo check --workspace
• node scripts/check-core-boundaries.mjs
• pnpm run check:repo-hygiene
• pnpm run check:github-config
• node scripts/install-cli.test.mjs
• node scripts/cli/package-contract.test.mjs
• native Windows install/reinstall/locked-file rollback test
• Windows static-CRT release build and ZIP smoke test, including PE dependency inspection
• cargo install --path src/apps/cli smoke test for both entrypoints
• PowerShell parser checks and git diff --check

Two independent adversarial reviews were completed from senior architecture and product-design perspectives. All reported P1/P2 findings were fixed; both final reviews found no remaining blocker, P1, or P2.