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/core/contractor/runtime-state.ts

@@ -0,0 +1,15 @@
+import path from "node:path";
+import fs from "node:fs";
+
+export function getContractorStateDir(workspace: string): string {
+  return path.join(workspace, ".openclaw", "contractor-agent");
+}
+
+export function getSessionMapPath(workspace: string): string {
+  return path.join(getContractorStateDir(workspace), "session-map.json");
+}
+
+export function ensureContractorStateDir(workspace: string): void {
+  const dir = getContractorStateDir(workspace);
+  fs.mkdirSync(dir, { recursive: true });
+}