fix(cli): transcribe names why whisper is missing and the one line that fixes it - #7366

What

When transcribe finds no whisper and cannot make one, the error now says why (for example "cannot build whisper.cpp: cmake not found on PATH", or the brew or build error) and gives one runnable line to fix it. On Linux that line is sudo apt-get install -y git cmake build-essential ... then re-run; on Windows it is a winget install line for Git, CMake and the VS Build Tools (or the upstream prebuilt whisper-bin-x64.zip, about 9 MB, via HYPERFRAMES_WHISPER_PATH). Also fixes a Windows build that succeeded but was never found: the Visual Studio generator writes build/bin/Release/whisper-cli.exe, and the lookup only tried build/bin/whisper-cli with no .exe, so the result was "Build completed but whisper-cli not found" (swallowed before this PR).

Why

A fresh Linux box ends with whisper_unavailable and, where Parakeet is unsupported (glibc older than 2.32), only a URL to follow. The brew and build failures were swallowed in ensureWhisper, so the real cause was never shown. Reproduced on a clean HOME on Ubuntu 20.04 with no cmake on PATH: npx hyperframes@latest transcribe a.wav prints "Captions skipped — whisper-cpp not found ... requires cmake", exit 1, and --json gives {"reason":"whisper_unavailable"}.

Related work

Refs the Discord report "Use your own voice recording" (transcribe fails with whisper_unavailable on a fresh install). This PR is the error half only. Whether a fresh box should fetch an engine itself (a prebuilt whisper.cpp, or Parakeet at about 670 MB) is a size decision and is not in this PR.

How

ensureWhisper collects each attempt's failure (brew, missing git or cmake, build error) into the WhisperUnavailableError message. getInstallInstructions returns a runnable line on Linux. Searched for an existing helper that formats install causes: none (grep -rn "getInstallInstructions" packages/cli/src finds only manager.ts and doctor.ts, which gets the new line too).

Test plan

• fails without the fix: whisper/manager.install.test.ts "names the missing build tool when whisper.cpp cannot be built", "gives a Linux user one runnable line to get a working engine", "gives a Windows user one runnable winget line, and finds a Release-built whisper-cli.exe" (3 failed with main's manager.ts, 5 pass at head).
• Unit tests added in whisper/manager.install.test.ts (names the missing cmake; Linux line; Windows winget line and a Release-built whisper-cli.exe is found). They fail with manager.ts reverted to main.
• manager.install.test.ts and api.test.ts pass on a remote box: 26 passed, exit 0.
• Manual: clean-HOME run on Linux reproduced the old message.
• Windows, real runner (windows-latest, clean cache, transcribe --engine whisper --model tiny.en on a spoken clip made with Windows speech synthesis): https://github.com/heygen-com/hyperframes/actions/runs/42398726579. main (job 128481661333) ends Captions skipped — whisper-cpp not found. Install: Build with cmake: ..., exit 1. This head (job 128481661473) builds whisper.cpp, finds whisper-cli.exe, and writes the words ("Hello", "from", "Hyperframes.", ...). The runner already has git and cmake, so the missing-cmake path and the winget line itself were not run there.
• Documentation updated (not applicable)
• Comments follow CONTRIBUTING.md

Size

A lone error-message fix that nothing else carries: the engine-fetch half is held for a size decision, and the own-recording work is a separate PR.

Not run: a real Windows machine (the Windows box was unreachable); the winget ids exist in microsoft/winget-pkgs (Git.Git, Kitware.CMake, Microsoft.VisualStudio.2022.BuildTools). The Windows test mocks the platform.