Add per-practice logins, a standalone login test, and pre-commit checks

The ChatGPT transcript showed each CAMBS practice has its own SFTP
account (YSMD is YAM62682 on io.myallylogin.com:14147), not one shared
entity login - so the wizard needed a way to set those without hand-
writing nine practice.json files. Option 5 does that, and the settings
screen now lists which login each practice will actually use.

test-login.bat tests one account on its own, with the details typed in
rather than read from a config, which isolates the account from whatever
a script is doing to the credentials. It reports password length,
stray whitespace, and $ / backtick characters - the last being the usual
reason a login works in the WinSCP window but fails from a script, since
"$pass" interpolates in PowerShell while '$pass' does not. On failure it
prints the authentication methods the server offered.

check.sh runs what has actually caught bugs here: non-ASCII characters,
"$name?" (? is legal in an unbraced variable name, so it renders empty -
this bit twice), parse errors, 5.1 syntax compatibility, and JSON validity.

test-login.bat

@@ -0,0 +1,4 @@
+@echo off
+REM Tests one SFTP/FTP login on its own. Nothing is read from a config file.
+powershell.exe -ExecutionPolicy Bypass -File "%~dp0Test-Login.ps1"
+pause