fix(ci): always ship checksums.txt; unglue update spinner (0.1.15)

[duyetbot]

Why

v0.1.15 anyr update warned release has no checksums.txt — skipping verification.
Root cause: release-binaries.yml notes (which uploaded checksums.txt) was skipped when any matrix build failed. Windows gh release upload often flakes with release not found, which skipped checksums for the whole tag.

Also: spinner glued the warning: (stable channel)warning: ...

What

1. checksums job — if: always() && !cancelled() after build/wasm. Downloads anyr-* from the tag, sha256sum, uploads checksums.txt --clobber. Fails if zero binaries.
2. Upload retry — scripts/gh-release-upload.sh retries 3× on release not found (Windows).
3. Notes after checksums — bench/notes cannot block checksums; notes continue-on-error.
4. Beta CI — test -s dist/checksums.txt before gh release create.
5. Spinner — pause + newline before install warnings.

Launcher + update-channel work from #72 is already on main; this branch also contains those commits if GitHub shows a delta.

After merge: workflow_dispatch release-binaries for v0.1.15 so the tag gets checksums.txt.

[github-actions]

anyr size and startup

Startup is wall time for a cold anyr --version / anyr --help (median of 21 runs). Size is the stripped release binary, or the .wasm for the browser demo.

Size budget: anyr-linux-x86_64 must stay ≤ 4.0 MiB (4194304 bytes) stripped.

Asset	Kind	Size	--version median	--help median
anyr-darwin-arm64	native	2.8 MiB	4.48 ms	4.23 ms
anyr-darwin-x86_64	native	3.0 MiB	44.28 ms	41.08 ms
anyr-linux-arm64	native	2.8 MiB	0.84 ms	0.84 ms
anyr-linux-x86_64	native	3.1 MiB	1.04 ms	1.0 ms
anyr-windows-x86_64.exe	native	2.6 MiB	9.23 ms	9.26 ms
anyr.wasm	wasm	180.1 KiB	—	—

Budget check: ok

raw timings

[
  {
    "asset": "anyr-darwin-arm64",
    "kind": "native",
    "path": "/Users/runner/work/cli/cli/anyr-darwin-arm64",
    "bytes": 2949544,
    "size": "2.8 MiB",
    "version": "0.1.15 (built 2026-09-16 11:57:52)",
    "target": "aarch64-apple-darwin",
    "os": "macos-latest",
    "startup_version": {
      "n": 21,
      "min_ms": 4.3,
      "median_ms": 4.48,
      "p95_ms": 5.27,
      "mean_ms": 4.66
    },
    "startup_help": {
      "n": 21,
      "min_ms": 3.7,
      "median_ms": 4.23,
      "p95_ms": 6.31,
      "mean_ms": 4.66
    }
  },
  {
    "asset": "anyr-darwin-x86_64",
    "kind": "native",
    "path": "/Users/runner/work/cli/cli/anyr-darwin-x86_64",
    "bytes": 3159408,
    "size": "3.0 MiB",
    "version": "0.1.15 (built 2026-09-16 11:57:23)",
    "target": "x86_64-apple-darwin",
    "os": "macos-latest",
    "startup_version": {
      "n": 21,
      "min_ms": 34.5,
      "median_ms": 44.28,
      "p95_ms": 58.09,
      "mean_ms": 45.59
    },
    "startup_help": {
      "n": 21,
      "min_ms": 34.39,
      "median_ms": 41.08,
      "p95_ms": 52.04,
      "mean_ms": 44.9
    }
  },
  {
    "asset": "anyr-linux-arm64",
    "kind": "native",
    "path": "/home/runner/work/cli/cli/anyr-linux-arm64",
    "bytes": 2888744,
    "size": "2.8 MiB",
    "version": "0.1.15 (built 2026-09-16 11:56:52)",
    "target": "aarch64-unknown-linux-gnu",
    "os": "ubuntu-24.04-arm",
    "startup_version": {
      "n": 21,
      "min_ms": 0.8,
      "median_ms": 0.84,
      "p95_ms": 1.0,
      "mean_ms": 0.85
    },
    "startup_help": {
      "n": 21,
      "min_ms": 0.78,
      "median_ms": 0.84,
      "p95_ms": 0.9,
      "mean_ms": 0.84
    }
  },
  {
    "asset": "anyr-linux-x86_64",
    "kind": "native",
    "path": "/home/runner/work/cli/cli/anyr-linux-x86_64",
    "bytes": 3253576,
    "size": "3.1 MiB",
    "version": "0.1.15 (built 2026-09-16 11:56:49)",
    "target": "x86_64-unknown-linux-gnu",
    "os": "ubuntu-latest",
    "startup_version": {
      "n": 21,
      "min_ms": 1.01,
      "median_ms": 1.04,
      "p95_ms": 1.09,
      "mean_ms": 1.05
    },
    "startup_help": {
      "n": 21,
      "min_ms": 0.99,
      "median_ms": 1.0,
      "p95_ms": 1.06,
      "mean_ms": 1.01
    }
  },
  {
    "asset": "anyr-windows-x86_64.exe",
    "kind": "native",
    "path": "D:\\a\\cli\\cli\\anyr-windows-x86_64.exe",
    "bytes": 2694656,
    "size": "2.6 MiB",
    "version": "0.1.15 (built 2026-09-16T11:58:21Z)",
    "target": "x86_64-pc-windows-msvc",
    "os": "windows-latest",
    "startup_version": {
      "n": 21,
      "min_ms": 8.9,
      "median_ms": 9.23,
      "p95_ms": 9.8,
      "mean_ms": 9.33
    },
    "startup_help": {
      "n": 21,
      "min_ms": 8.52,
      "median_ms": 9.26,
      "p95_ms": 9.62,
      "mean_ms": 9.18
    }
  },
  {
    "asset": "anyr.wasm",
    "kind": "wasm",
    "path": "/home/runner/work/cli/cli/target/wasm-pkg/anyr_cli_bg.wasm",
    "bytes": 184424,
    "size": "180.1 KiB",
    "version": "wasm",
    "target": "wasm32-unknown-unknown",
    "os": ""
  }
]