refactor: restructure to plugin/ + services/ layout and add per-turn bootstrap injection

- Migrate src/ → plugin/ (plugin/core/, plugin/web/, plugin/commands/)
  and src/mcp/ → services/ per OpenClaw plugin dev spec
- Add Gemini CLI backend (plugin/core/gemini/sdk-adapter.ts) with GEMINI.md
  system-prompt injection
- Inject bootstrap as stateless system prompt on every turn instead of
  first turn only: Claude via --system-prompt, Gemini via workspace/GEMINI.md;
  eliminates isFirstTurn branch, keeps skills in sync with OpenClaw snapshots
- Fix session-map-store defensive parsing (sessions ?? []) to handle bare {}
  reset files without crashing on .find()
- Add docs/TEST_FLOW.md with E2E test scenarios and expected outcomes
- Add docs/claude/BRIDGE_MODEL_FINDINGS.md with contractor-probe results

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

plugin/openclaw.plugin.json

@@ -0,0 +1,28 @@
+{
+  "id": "contractor-agent",
+  "name": "Contractor Agent",
+  "version": "0.1.0",
+  "description": "Turns Claude Code into an OpenClaw-managed contractor agent",
+  "main": "index.ts",
+  "configSchema": {
+    "type": "object",
+    "additionalProperties": false,
+    "properties": {
+      "bridgePort": {
+        "type": "number",
+        "default": 18800,
+        "description": "Port for the contractor bridge sidecar HTTP server"
+      },
+      "bridgeApiKey": {
+        "type": "string",
+        "default": "contractor-bridge-local",
+        "description": "API key for the bridge sidecar (local use only)"
+      },
+      "permissionMode": {
+        "type": "string",
+        "default": "bypassPermissions",
+        "description": "Claude Code permission mode for contractor sessions"
+      }
+    }
+  }
+}