refactor: restructure PrismFacet per OpenClaw plugin spec

- plugin/ directory structure: hooks/, tools/, core/
- export default { id, name, register } entry format
- globalThis state management with lifecycle protection
- WeakSet dedup on before_prompt_build hook
- Tool uses inputSchema + execute (not parameters + handler)
- additionalProperties: false in config schema
- Core logic in plugin/core/ (no plugin-sdk dependency)
- Install/uninstall script (scripts/install.mjs)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

plugin/core/rule-store.ts

@@ -0,0 +1,56 @@
+import { readFileSync, writeFileSync } from "node:fs";
+
+export type RuleStore = Record<string, string>; // "router:key" → prompt file path
+
+const _G = globalThis as Record<string, unknown>;
+const RULES_KEY = "_prismFacetRules";
+const RULES_PATH_KEY = "_prismFacetRulesPath";
+
+function getRules(): RuleStore {
+  if (!_G[RULES_KEY] || typeof _G[RULES_KEY] !== "object") {
+    _G[RULES_KEY] = {};
+  }
+  return _G[RULES_KEY] as RuleStore;
+}
+
+function getRulesPath(): string {
+  return (_G[RULES_PATH_KEY] as string) || "";
+}
+
+function save(): void {
+  const p = getRulesPath();
+  if (!p) return;
+  writeFileSync(p, JSON.stringify(getRules(), null, 2) + "\n", "utf8");
+}
+
+export function initRuleStore(filePath: string): void {
+  _G[RULES_PATH_KEY] = filePath;
+  try {
+    const raw = readFileSync(filePath, "utf8");
+    _G[RULES_KEY] = JSON.parse(raw) as RuleStore;
+  } catch {
+    _G[RULES_KEY] = {};
+  }
+}
+
+export function addRule(router: string, key: string, promptFile: string): void {
+  getRules()[`${router}:${key}`] = promptFile;
+  save();
+}
+
+export function removeRule(router: string, key: string): boolean {
+  const rules = getRules();
+  const ruleKey = `${router}:${key}`;
+  if (!(ruleKey in rules)) return false;
+  delete rules[ruleKey];
+  save();
+  return true;
+}
+
+export function getRule(router: string, key: string): string | undefined {
+  return getRules()[`${router}:${key}`];
+}
+
+export function listRules(): Record<string, string> {
+  return { ...getRules() };
+}