feat: agent-to-agent platform on ZeroClaw 0.8.2 — rooms, delegation, A2A ingress

Builds on the v0.8.2 runtime. Four workstreams, all behind the §15 MCP door:

- Group rooms (Phase 1): migration 0026; N-way threads repo with a DM/room
  count-guard; chat.send {room} + room.create/invite/leave tools; RoomMessage
  -> room.message SSE; /api/claw-chat/rooms* APIs; Observer room badge.
- Per-claw door identity: door caller_agent resolves the X-ZeroClaw-Agent
  header (set by the fork) to the specific claw, falling back to roster[0].
- Gated delegation bridge (Phase 3): clawmates__delegate door tool drives a
  sibling via the existing /ws/chat ZeroClawDriveExecutor (not A2A); self-deny,
  per-workspace hourly budget, audit trail, untrusted-banner result. Native
  in-daemon delegation stays off (it would bypass the door).
- A2A tenant ingress (Phase 2): migration 0027 (workspace_a2a + a2a_tokens);
  runtime_provision enable_a2a_server/publish_claw; routes/a2a.rs tenant-aware
  proxy (per-workspace tokens, injected internal bearer, daemon stays internal,
  cards URL-rewritten to the cm-api edge); a2a.invoked taxonomy.

Tests: cm-db room repos, cm-runtime chat tools, door units. sqlx cache updated.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

.sqlx/query-47c1cee8591250819d22e87058c6011bebb77eaf93c1cfa2535db42221d8ecf3.json

@@ -1,34 +0,0 @@
-{
-  "db_name": "PostgreSQL",
-  "query": "SELECT tokens_in, tokens_out, credits FROM usage_events\n               WHERE workspace_id = $1",
-  "describe": {
-    "columns": [
-      {
-        "ordinal": 0,
-        "name": "tokens_in",
-        "type_info": "Int8"
-      },
-      {
-        "ordinal": 1,
-        "name": "tokens_out",
-        "type_info": "Int8"
-      },
-      {
-        "ordinal": 2,
-        "name": "credits",
-        "type_info": "Numeric"
-      }
-    ],
-    "parameters": {
-      "Left": [
-        "Uuid"
-      ]
-    },
-    "nullable": [
-      false,
-      false,
-      false
-    ]
-  },
-  "hash": "47c1cee8591250819d22e87058c6011bebb77eaf93c1cfa2535db42221d8ecf3"
-}