feat(tuku): 图库 M3 骨架——书库浏览/主题同步/阅读器与锁屏接缝

- 新增顶层 tuku/ 工程（package dev.tuku.app、二进制 tuku）：app.c/internal 头/logic/ui 分层、app.json、build/pack 脚本
- 书库：从 TF 卡根浏览文件夹，含图目录=一本书；logic/library 纯 C 扫描+自然排序（page2<page10）
- 流式缩略图：后台线程解码+meow_img_downscale(96)，首帧/滚动不阻塞；磁盘缓存 MeowData/<pkg>/cache（mtime 失效+LRU）
- 列表 meow_listview 虚拟化 + meow_scroll fling/snap；行=缩略图+目录名+页数
- 主题：全部语义色 + meow_theme_add_listener 即时重绘；明暗/风格族两态可读
- 导航：meow_view page push/pop、TopAppBar ⚙→设置；reader/settings/lock 最小桩
- 接缝：mr_reader_get/set_direction（默认 RTL）、lock_view_should_show()（桩 0）
- 宿主 gcc 测试 46 项 PASS；交叉构建静态 MIPS32r2 ELF、-Wall -Wextra 零警告

tuku/ui/lock/lock.c

@@ -0,0 +1,55 @@
+/* ui/lock/lock.c — 锁屏页（ACT_LOCK）M3 桩 + M5 接缝。
+ *
+ * M5 在此实现「APP 启动 PIN」：lock_view_should_show() 读配置决定是否锁，
+ * 锁屏页负责 PIN 输入/校验后 page_pop 回书库。本批桩恒返回 0（不锁），页面仅可编译占位。
+ */
+#include "tuku_internal.h"
+
+static mr_page_ctrl g_ctrl;
+
+int lock_view_should_show(void)
+{
+    return 0;   /* M5：读 APP 启动 PIN 配置后返回 1 */
+}
+
+static void lock_draw(meow_view *v, const meow_theme *th, void *ctx)
+{
+    (void)v; (void)ctx;
+    int w = meow_ui_width();
+    int h = meow_ui_height();
+    int cy = h / 2;
+
+    meow_ui_text_center(w / 2, cy - 80, "LOCKED", th->font_title, th->primary);
+    meow_ui_text_center(w / 2, cy - 36, "Startup PIN (M5)", th->font_body, th->onSurface);
+    meow_ui_text_center(w / 2, cy + 8, "PIN entry will be implemented in M5",
+                        th->font_body, th->onSurfaceVariant);
+}
+
+static void lock_page_enter(meow_view *v, void *ctx)
+{
+    ((mr_page_ctrl *)ctx)->active = 1;
+    v->x = 0;
+    v->y = 0;
+    v->w = meow_ui_width();
+    v->h = meow_ui_height();
+    meow_ui_set_fullscreen(0);
+    meow_ui_set_page_bg(meow_theme_get()->bg);
+    mr_nav_report();
+    meow_ui_paint_full();
+}
+
+static void lock_page_leave(meow_view *v, void *ctx)
+{
+    (void)v;
+    ((mr_page_ctrl *)ctx)->active = 0;
+}
+
+meow_view *lock_view_create(void)
+{
+    static const meow_view_hooks h = {
+        .on_enter = lock_page_enter,
+        .on_leave = lock_page_leave,
+        .on_draw  = lock_draw,
+    };
+    return meow_view_create(ACT_LOCK, MEOW_VIEW_ACTIVITY, &h, &g_ctrl);
+}