feat(schema): add consecutive_auth_failures column on federation_peers

Tracks HMAC-failure count separately from consecutive_failures (network
errors). Auth failures and network failures have different resolution
paths; mixing them would let a single successful retry after a network
blip mask real secret desync.

Part of backlog #19 — outbox auth-failure recovery.

Note: drizzle-kit generated the 0003 SQL with an unexpected CREATE TABLE
for peer_approval_requests because the 0002 migration was authored
manually without a corresponding 0002_snapshot.json (see 14041e9). The
generated SQL has been trimmed to the single intended ALTER TABLE. The
regenerated 0003_snapshot.json correctly reflects the full current
schema, so future migrations will diff cleanly.

packages/server/drizzle/meta/_journal.json

@@ -22,6 +22,13 @@
       "when": 1776689384005,
       "tag": "0002_peer_approval_requests",
       "breakpoints": true
+    },
+    {
+      "idx": 3,
+      "version": "6",
+      "when": 1776789567488,
+      "tag": "0003_classy_loki",
+      "breakpoints": true
     }
   ]
 }