Probe per-user Git Bash and Scoop before falling back to PATH on Windows

Stock Windows 10/11 ships C:\Windows\System32\bash.exe (the WSL
launcher) as the first match for `where bash`. WSL's bash cannot
execute Windows-style script paths, so when Git Bash is installed
outside the two standard system locations -- specifically the
per-user "Only for me" Git for Windows installer
(%LOCALAPPDATA%\Programs\Git) or a Scoop install
(%USERPROFILE%\scoop\apps\git\current\usr\bin) -- run-hook.cmd
silently fails: WSL prints "Windows Subsystem for Linux must be
updated", the script returns 0, and Superpowers' SessionStart
bootstrap is never injected. From the user's perspective skills
auto-trigger inconsistently or not at all, with no surfaced error.

Add explicit probes for both locations between the existing system-
wide Git for Windows checks and the `where bash` fallback. Also add
a comment to the fallback documenting the WSL-launcher trap so future
maintainers understand why the explicit probes must come first.

Verified on a Windows 11 VM (dockur/windows 11, Git Bash 2.x, Node
22):
- System Git present: existing probe still matches (no regression)
- System Git absent, per-user Git present via junction: new probe
  matches, hook produces valid 6422-byte JSON, exit 0
- All Git probes absent: confirmed WSL trap fires
  ("Windows Subsystem for Linux must be updated") and the hook exits 0
  silently, demonstrating the original bug

Existing tests/hooks/test-session-start.sh still passes on macOS (7/7).

Reported by @ytchenak in #1607.

Co-authored-by: ytchenak <ytchenak@users.noreply.github.com>
Closes #1607.

hooks/run-hook.cmd

@@ -26,8 +26,21 @@ if exist "C:\Program Files (x86)\Git\bin\bash.exe" (
     "C:\Program Files (x86)\Git\bin\bash.exe" "%HOOK_DIR%%~1" %2 %3 %4 %5 %6 %7 %8 %9
     exit /b %ERRORLEVEL%
 )
+REM Per-user Git for Windows installer ("Only for me" / winget user scope)
+if exist "%LOCALAPPDATA%\Programs\Git\bin\bash.exe" (
+    "%LOCALAPPDATA%\Programs\Git\bin\bash.exe" "%HOOK_DIR%%~1" %2 %3 %4 %5 %6 %7 %8 %9
+    exit /b %ERRORLEVEL%
+)
+REM Scoop user install (`scoop install git`)
+if exist "%USERPROFILE%\scoop\apps\git\current\usr\bin\bash.exe" (
+    "%USERPROFILE%\scoop\apps\git\current\usr\bin\bash.exe" "%HOOK_DIR%%~1" %2 %3 %4 %5 %6 %7 %8 %9
+    exit /b %ERRORLEVEL%
+)
 
-REM Try bash on PATH (e.g. user-installed Git Bash, MSYS2, Cygwin)
+REM Try bash on PATH (e.g. user-installed Git Bash, MSYS2, Cygwin). Note that
+REM on stock Windows 10/11 `where bash` resolves to C:\Windows\System32\bash.exe
+REM (the WSL launcher), which fails on Windows-style script paths. The explicit
+REM probes above must therefore be exhausted first.
 where bash >nul 2>nul
 if %ERRORLEVEL% equ 0 (
     bash "%HOOK_DIR%%~1" %2 %3 %4 %5 %6 %7 %8 %9