initial: identity resolution plugin

- Plugin manifest (plugin.yaml) with pre_gateway_dispatch + on_session_start hooks
- /identity slash command for config management
- Honcho injector patch docs (6 lines in plugins/memory/honcho/__init__.py)
- Config file at /opt/data/identity-config.json for persistence
- Kanban task body convention: context_peer: <name>
- Sample config with thierry/catherine mappings

Architecture: user-installed plugin (hooks + CLI) + 6-line Honcho bundled plugin change

config.sample.json

@@ -0,0 +1,14 @@
+{
+  "mappings": [
+    {"platform": "discord", "id": "479136126737711105", "peer": "thierry"},
+    {"platform": "telegram", "id": "",                "peer": "thierry"},
+    {"platform": "terminal", "id": "default",          "peer": "thierry"},
+    {"platform": "matrix",   "id": "",                "peer": "thierry"}
+  ],
+  "boards": {
+    "default":    "thierry",
+    "catherine":  "catherine"
+  },
+  "fallback_peer": "user",
+  "enforce_context_peer": true
+}