doctor: verify timeout/gtimeout is available (Ralph loop requires it)

[selimdev00]

Problem

bmalph doctor reports "all checks OK" on a machine where the Ralph loop cannot actually run. The loop wraps every agent call in timeout/gtimeout (.ralph/lib/timeout_utils.sh), but doctor never verifies that command exists.

On a fresh macOS without GNU coreutils, the result is:

• bmalph doctor -> all green
• bmalph run -> dies on loop iteration [P0] mergeClaudeMd truncates user content after BMAD section #1:

  [ERROR] Claude Code exited: error (code 1)
    stderr: Error: No timeout command available on this system
    Install GNU coreutils on macOS: brew install coreutils
  

So a green doctor is not a guarantee the loop will start.

Fix

Add a timeout-available check to the core registry, right after the jq check (both are loop runtime deps). It probes the same way the loop resolves the binary - via command -v inside bash - so it matches the loop's actual environment rather than the host PATH:

• macOS: command -v gtimeout || command -v timeout
• Linux/other: command -v timeout

On failure it fails the check with a platform-specific hint (brew install coreutils on macOS, apt-get install coreutils on Linux, MSYS2 on Windows). On success it reports the resolved binary, e.g. timeout command available (gtimeout).

Tests

• Unit tests for checkTimeout (label, pass + resolved-binary detail, macOS gtimeout-first probe, failure hint).
• Updated registry assertions (length 18 -> 19, new id ordered after jq-available).
• Full unit suite (1839) and the doctor e2e suite pass.