Archify Sync server, Dockerfile and Helm chart

Rust server (axum, yrs, sqlx/PostgreSQL): live shared models over the y-websocket protocol, versions, browser sign-in with PKCE, invites, single sign-on through OIDC, metrics. Docker image on distroless, compose file, and a Helm chart with one pod, optional bundled PostgreSQL and secrets from existing Secrets.

crates/store/migrations/0002_identities.sql

@@ -0,0 +1,13 @@
+-- Accounts signed in through an identity provider (OIDC): the provider's
+-- issuer and subject name the person; the account is ours.
+
+CREATE TABLE identities (
+    issuer        text NOT NULL,
+    subject       text NOT NULL,
+    account_id    uuid NOT NULL REFERENCES accounts (id) ON DELETE CASCADE,
+    email         text,
+    created_at    timestamptz NOT NULL DEFAULT now(),
+    last_seen_at  timestamptz NOT NULL DEFAULT now(),
+    PRIMARY KEY (issuer, subject)
+);
+CREATE INDEX identities_account ON identities (account_id);