refactor(auth): extract connector definitions out of auth.ts (#6203)

auth.ts had grown to 3,927 lines, of which ~2,340 were the genericOAuth
connector list — the OAuth apps a workspace connects tools to, as distinct from
the handful of providers used to sign in to Sim. Adding a connector meant
editing the same file that configures sessions, database hooks and Stripe.

Moves that list to lib/auth/connectors/providers.ts behind
buildConnectorProviders(), and relocates getMicrosoftUserInfoFromIdToken to
lib/oauth/microsoft.ts alongside the three Microsoft helpers it already depends
on. auth.ts drops to 1,489 lines and reads as auth configuration again.

Pure move, verified mechanically: the connector array is token-identical after
stripping whitespace, and all 179 template literals emit byte-identical strings
(the one apparent diff was reindentation inside a ${} expression, not text).
Behavior, evaluation order and log scopes are unchanged; the array is still
built once, when betterAuth() runs.

The explicit GenericOAuthConfig[] return type is required, not cosmetic —
inline, the entries were contextually typed by the config property. Without it
prompt: 'consent' widens to string and every getUserInfo parameter becomes
implicitly any.

Author: waleedlatif1