Switch database IDs from TEXT to native UUID

Consolidate 16 migrations into one with UUID columns for all entity
IDs. TEXT is kept only for polymorphic fields (audit_logs.actor_id,
resource_id) and template names. The id package now generates UUIDs
via google/uuid, with Format*/Parse* helpers for the prefixed wire
format (sb-{uuid}, usr-{uuid}, etc.). Auth context, services, and
handlers pass pgtype.UUID internally; conversion to/from prefixed
strings happens at API and RPC boundaries. Adds PlatformTeamID
(all-zeros UUID) for shared resources.

db/queries/sandboxes.sql

@@ -50,7 +50,7 @@ WHERE id = $1;
 UPDATE sandboxes
 SET status = $2,
     last_updated = NOW()
-WHERE id = ANY($1::text[]);
+WHERE id = ANY($1::uuid[]);
 
 -- name: ListActiveSandboxesByTeam :many
 SELECT * FROM sandboxes
@@ -72,4 +72,4 @@ WHERE host_id = $1 AND status IN ('running', 'starting', 'pending');
 UPDATE sandboxes
 SET status       = 'running',
     last_updated = NOW()
-WHERE id = ANY($1::text[]) AND status = 'missing';
+WHERE id = ANY($1::uuid[]) AND status = 'missing';