feat(meditate): Meditate's server, its sealed tables, and SimpleLogin's way back to it

halkyon_meditate_server and its generated client, copied from Todo's
and stripped to the module, the register and the sync engine (ADR 0038,
D1, D7): content_key, meditate_settings and sitting, synced and sealed,
each indexing spaceId and deleted with the person's space; two
migrations, the initial one and sittings (purely additive, the ADR
explains the SQL); ports 8280 to 8282 and PostgreSQL 8290 (D13).
Tests: the module's basics naming `meditate`, the sync engine refusing
calls without a session, the register's modes, and a person's deletion
taking their rows alone.

halkyon_base's forwarding page knows Meditate's ways back
(meditate-loopback on 43826, meditate-scheme app.halkyon.meditate),
which halkyon_app's repository names among the apps' ports.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/meditate/halkyon_meditate_server/config/generator.yaml

@@ -0,0 +1,16 @@
+type: server
+
+client_package_path: ../halkyon_meditate_client
+server_test_tools_path: test/integration/test_tools
+
+# Private data sync through serverpod_offline_sync (ADR 0001, ADR 0038's D7): its
+# module, and the experimental `database: sync` for the models it syncs.
+modules:
+  serverpod_offline_sync:
+    nickname: offline_sync
+  # What every Halkyon server has (ADR 0014): `client.modules.base` in the app.
+  halkyon_base:
+    nickname: base
+
+experimental_features:
+  databaseSync: true