Implement V2 registration support (#7765)

* Implement V2 registration support

* Require the client version header on every login, like upstream

Every user login (password, user API key, SSO, including a first SSO login)
now needs the Bitwarden-Client-Version header, for V1 accounts too. V2
accounts need 2026.10.1, or 2026.10.2 for the desktop app, upstream's
current minimum.

* Escape the email in the client version log line

On a first SSO login the email comes from the identity provider and isn't validated yet, so a newline in it could add a line to the log.

src/config.rs

@@ -1516,6 +1516,8 @@ pub const SUPPORTED_FEATURE_FLAGS: &[&str] = &[
     // Key Management Team
     "biometrics-sdk-ipc",
     "windows-native-credential-sync",
+    "enable-account-encryption-v2-jit-password-registration",
+    "pm-27278-v2-password-registration",
     // Mobile Team
     "pm-34171-card-scanner",
     // Platform Team