Add waterlog app interface

[bruno-f-cruz]

Adds WaterlogApp, an ExecutableApp for launching the AIBS MPE waterlog executable with settings-driven CLI arguments.

Details:

• WaterlogSettings (pydantic-settings) — captures username, mouse ID, weight, water earned/supplement, comment
• WaterlogApp.run() uses LocalDetachedExecutor (see Add LocalDetachedExecutor #249) — waterlog is launched fire-and-forget since the caller doesn't need to wait for it
• Falls back to shutil.which("waterlog.exe") if the default %PROGRAMFILES%\AIBS_MPE\waterlog\waterlog.exe is not found

Depends on #249 — rebase/merge that first.

[bruno-f-cruz]

@micahwoodard @patricklatimer This is the pattern I had in mind when using CLI apps with executors. Never got around to formalizing it, but in case you are interested. These BaseSettings could obviously be defined elsewhere and imported.