feat: add profile fields for local users

DB→domain→API→AP→frontend end-to-end. Fields stored as
JSONB, exposed via PATCH /users/me, serialized as AP
PropertyValue attachment. Editor in federation settings,
display on profile card.

crates/adapters/postgres-federation/Cargo.toml

@@ -12,6 +12,7 @@ tracing = { workspace = true }
 async-trait = { workspace = true }
 anyhow = { workspace = true }
 url = { workspace = true }
+serde_json = { workspace = true }
 
 [dev-dependencies]
 tokio = { workspace = true, features = ["full"] }