Tranquil is a community AT Protocol PDS — a single Rust binary rather than
the reference server's Node.js runtime, and a superset of it. It can now be
hosted from an Aspire AppHost and administered with PdsAdminClient, through
the same APIs the reference PDS uses.

AddAtProtoTranquilPds adds the atcr.io/tranquil.farm/tranquil-pds container.
Tranquil keeps its repositories in PostgreSQL, so the call also provisions a
server and database and waits on them; WithDatabase / WithDatabaseUrl point
it at one you already have and drop the generated resources from the model.
It is handed a postgres:// URI, not the ADO.NET connection string Aspire's
PostgresDatabaseResource exposes, which would not parse.

The difference an application has to care about is authentication. The
reference PDS has one server-wide admin password used with HTTP Basic;
Tranquil has none, and flags individual accounts as administrators
authenticated with an ordinary session. PdsAdminOptions.Authentication
selects the scheme and AdminIdentifier names the account. Under AdminAccount
the client signs in lazily — the account may not exist when the client is
resolved — reuses the session, and re-authenticates once if the server
rejects it.

The administrator account is deliberately not created by the AppHost:
Tranquil flags the first account on an empty instance as an administrator,
so the application registers it with CreateAccountAsync, which works
unauthenticated. Its handle is derived from the hostname rather than fixed,
so WithHostname alone leaves a handle the server will issue, and defaults to
pdsadmin rather than admin, which Tranquil rejects as reserved.

Running locally the container also gets the relaxations a development
instance needs, and none of them when publishing. Two are load-bearing: an
empty Tranquil mints a bootstrap invite code only to its log, and login is
blocked until an account has a verified communication channel. At Tranquil's
own defaults no account could be created locally and none could sign in.

closes #78

@@ -0,0 +139,4 @@
+                if (resource.DevelopmentMode)
+                {
+                    ApplyDevelopmentDefaults(context.EnvironmentVariables);
+                }