feat: enforce client spool quota tiers

internal/client/spool/migrations.go

@@ -60,6 +60,9 @@ CREATE TABLE commands (
   command_revision INTEGER NOT NULL CHECK(command_revision > 0),
   phase INTEGER NOT NULL CHECK(phase BETWEEN 1 AND 11),
   terminal INTEGER NOT NULL DEFAULT 0 CHECK(terminal IN (0, 1)),
+  output_charged_bytes INTEGER NOT NULL DEFAULT 0 CHECK(output_charged_bytes >= 0),
+  total_charged_bytes INTEGER NOT NULL CHECK(total_charged_bytes >= 0),
+  closeout_remaining_bytes INTEGER NOT NULL CHECK(closeout_remaining_bytes >= 0),
   next_local_ordinal INTEGER NOT NULL DEFAULT 1 CHECK(next_local_ordinal > 0),
   next_event_seq INTEGER NOT NULL DEFAULT 1 CHECK(next_event_seq > 0),
   last_server_ack INTEGER NOT NULL DEFAULT 0 CHECK(last_server_ack >= 0),
@@ -72,6 +75,8 @@ CREATE TABLE events (
   event_kind INTEGER NOT NULL CHECK(event_kind > 0),
   compression INTEGER NOT NULL CHECK(compression IN (1, 2)),
   raw_bytes INTEGER NOT NULL CHECK(raw_bytes >= 0),
+  charged_bytes INTEGER NOT NULL CHECK(charged_bytes > 0),
+  output INTEGER NOT NULL CHECK(output IN (0, 1)),
   payload BLOB NOT NULL,
   payload_sha256 BLOB NOT NULL CHECK(length(payload_sha256) = 32),
   created_at INTEGER NOT NULL,
@@ -79,6 +84,12 @@ CREATE TABLE events (
   UNIQUE(issue_uuid, event_seq)
 ) STRICT, WITHOUT ROWID;
 CREATE INDEX events_send_window ON events(issue_uuid, event_seq, local_ordinal);
+CREATE TABLE spool_counters (
+  singleton INTEGER PRIMARY KEY CHECK(singleton = 1),
+  client_total_charged_bytes INTEGER NOT NULL CHECK(client_total_charged_bytes >= 0),
+  charge_version INTEGER NOT NULL CHECK(charge_version = 1)
+) STRICT;
+INSERT INTO spool_counters(singleton, client_total_charged_bytes, charge_version) VALUES (1, 0, 1);
 CREATE TABLE command_tombstones (
   issue_uuid BLOB PRIMARY KEY CHECK(length(issue_uuid) = 16),
   immutable_sha256 BLOB NOT NULL CHECK(length(immutable_sha256) = 32),