ci(cli): build bitfun-cli per release and notify homebrew-tap

[harryfan1985]

Refs #757

Adds .github/workflows/cli-package.yml which, on every published release:

• Builds bitfun-cli natively on four runners — macos-15 (arm64), macos-15-intel (x86_64), ubuntu-latest (x86_64), ubuntu-24.04-arm (aarch64) — avoiding cross-compilation entirely.
• Runs --version and --help smoke tests to catch dynamic-linker / missing-lib failures before publishing.
• Packages each build as bitfun-cli-<version>-<rust-target>.tar.gz (binary + LICENSE + README + themes/ + prompts/), generates a per-archive .sha256 and a combined SHA256SUMS.
• Uploads everything to the corresponding GitHub Release via softprops/action-gh-release@v2.
• Fires a repository_dispatch to GCWing/homebrew-tap so the bitfun-cli formula can auto-bump. Safe no-op when HOMEBREW_TAP_DISPATCH_TOKEN is not configured — forks and the pre-tap window are unaffected.

The workflow shape (triggers, prepare job, version-resolution logic, concurrency group naming) mirrors the existing desktop-package.yml for consistency.

Why prebuilt binaries (not a from-source brew formula)

bitfun-cli pulls in the full bitfun-core workspace via the product-full feature. A from-source brew install would take 5–10 minutes per user and require a Rust toolchain — unfriendly for terminal users. Shipping prebuilt tarballs keeps brew install bitfun-cli near-instant.

Smoke-test plan after merge

1. Trigger via workflow_dispatch with tag_name=v0.2.7 and upload_to_release=false to validate the four-target matrix without touching the release.
2. Once green, configure HOMEBREW_TAP_DISPATCH_TOKEN in repo secrets and push the prepared GCWing/homebrew-tap repo.
3. Validate end-to-end on the next real release: release published → 4 tarballs uploaded → tap auto-bump PR opened.

Related (separate repo, not in this PR)

• GCWing/homebrew-tap formula + bump workflow are prepared and pending push to the new tap repo.
• homebrew-core submission deferred per the issue plan, gated on 1.0.0 + adoption.