refactor: notify/footer 持久配置收编到 config/，chrome bridge 地址固定

仓库规则要求 config/ 为唯一配置来源、不以环境变量作持久默认值：
- pi-notify 改读 config/pi-notify.json（逐字段校验回退，复用原 parsers 钳制）
- pi-minimal-footer 改读 config/pi-minimal-footer.json
- pi-chrome 移除 PI_CHROME_BRIDGE_HOST/PORT，固定 127.0.0.1:17318
  （浏览器端 service_worker.js 硬编码同一地址，单侧可配只会断连）

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pi-minimal-footer/settings.ts

@@ -0,0 +1,30 @@
+import { readFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+
+export interface FooterSettings {
+  showCwd: boolean;
+  showBranch: boolean;
+}
+
+// Bundle-level `config/` is the single source of truth: the extension reads
+// `config/pi-minimal-footer.json` from inside the installed bundle (resolved
+// relative to this source file), never environment variables.
+export const FOOTER_CONFIG_PATH = fileURLToPath(
+  new URL("../config/pi-minimal-footer.json", import.meta.url),
+);
+
+export function readFooterSettings(configPath: string = FOOTER_CONFIG_PATH): FooterSettings {
+  try {
+    const parsed = JSON.parse(readFileSync(configPath, "utf8")) as unknown;
+    const raw =
+      parsed !== null && typeof parsed === "object" && !Array.isArray(parsed)
+        ? (parsed as Record<string, unknown>)
+        : {};
+    return {
+      showCwd: typeof raw.showCwd === "boolean" ? raw.showCwd : true,
+      showBranch: typeof raw.showBranch === "boolean" ? raw.showBranch : true,
+    };
+  } catch {
+    return { showCwd: true, showBranch: true };
+  }
+}