feat: M6.43 — reader分段流式读取(Phase1,只txt) + 面板前台管理/返回回桌面按钮

- reader分段(只txt): core/seg.{h,c} 512KB码位对齐切段(尾字完整)+manifest+按需读单段; book.c rd_book_open只布局每页所在段(治CPU100%/返回无效) load_seg只读当前段(非txt原路径); reader.c 进度实时保存(翻页/刮擦/字号/编码dirty+on_tick节流落盘+退出即时写,锚点存段号,崩溃不丢进度); rdtxt.c fread替代fgetc(去开书扫描卡顿); Phase2(双段拼接+4%释放)留待
- 面板: /api/ams/bg加fg/fg_count(后台保持向后兼容)+POST /api/ams/:pkg/killfg(前台救命:优先am kill,launcher拒则pid直信号SIGTERM->SIGKILL绕过门控)+前端/#/bg前台组'终止'绿徽标+确认弹窗(一键清仍只后台不误杀前台); POST /api/input/gesture(返回=左缘右滑/回桌面=底部上滑,注入滑动轨迹复用SDK手势)+前端屏幕控制页加返回/回桌面MD3按钮

0warning;宿主test_reader_core 72-0/seg_smoke 19-0/loaders_smoke/book_smoke/formats_smoke PASS;面板selftest/node check PASS

patch_v2/reader_app/build_reader.sh

@@ -91,6 +91,10 @@ echo "==> host core test (R1)"
 $HOST_CC -O2 -Wall -Wextra -Icore -I. test/test_reader_core.c core/rdenc.c core/rdlayout.c core/rdtxt.c -o test/test_reader_core_host -lm
 ./test/test_reader_core_host
 
+echo "==> host seg test (R3.2)"
+$HOST_CC -O2 -Wall -Wextra -Icore test/seg_smoke.c core/seg.c core/rdenc.c -o test/seg_smoke_host -lm
+./test/seg_smoke_host
+
 echo "==> host loaders test"
 HOBJ="$OBJ/host"; mkdir -p "$HOBJ"
 for f in vendor/miniz/miniz_tinfl.c vendor/miniz/miniz_tdef.c vendor/miniz/miniz_zip.c vendor/miniz/miniz.c; do
@@ -115,21 +119,21 @@ timeout 120 qemu-mipsel ./test/rdft_smoke_mipsel "${FONT:-$ROOT/font/src/MiSans-
 # ---------- 6) qemu-mipsel 书桥冒烟（TXT + 四格式） ----------
 echo "==> mipsel book smoke (TXT)"
 $CC -Os -static -Wall -Wextra -Iapp -Icore -Iengine $FT_INCS $COREINC test/book_smoke.c \
-  app/book.c core/rdenc.c core/rdlayout.c core/rdtxt.c core/rdxml.c core/rdhtml.c core/rdsb.c core/rdzip.c \
+  app/book.c core/rdenc.c core/rdlayout.c core/rdtxt.c core/seg.c core/rdxml.c core/rdhtml.c core/rdsb.c core/rdzip.c \
   core/rdsrc.c core/rdepub.c core/rdfb2.c core/rdmobi.c core/rdcbz.c engine/rdft.c \
   "$OBJ"/mz_*.o "$OBJ"/lm_*.o "$OBJ"/rdimg.o "$SYSROOT/lib/libz.a" "$FT_BUILD/libfreetype.a" -o test/book_smoke_mipsel
 timeout 120 qemu-mipsel ./test/book_smoke_mipsel "${FONT:-$ROOT/font/src/MiSans-Regular.otf}"
 
 echo "==> mipsel formats smoke"
 $CC -Os -static -Wall -Wextra -Iapp -Icore -Iengine $FT_INCS $COREINC test/formats_smoke.c \
-  app/book.c core/rdenc.c core/rdlayout.c core/rdtxt.c core/rdxml.c core/rdhtml.c core/rdsb.c core/rdzip.c \
+  app/book.c core/rdenc.c core/rdlayout.c core/rdtxt.c core/seg.c core/rdxml.c core/rdhtml.c core/rdsb.c core/rdzip.c \
   core/rdsrc.c core/rdepub.c core/rdfb2.c core/rdmobi.c core/rdcbz.c engine/rdft.c \
   "$OBJ"/mz_*.o "$OBJ"/lm_*.o "$OBJ"/rdimg.o "$SYSROOT/lib/libz.a" "$FT_BUILD/libfreetype.a" -o test/formats_smoke_mipsel
 timeout 150 qemu-mipsel ./test/formats_smoke_mipsel "${FONT:-$ROOT/font/src/MiSans-Regular.otf}" /tmp/rd_samples
 
 # ---------- 7) reader 二进制（mipsel 静态） ----------
 echo "==> reader binary"
-CORE_L="core/rdenc.c core/rdlayout.c core/rdtxt.c core/rdxml.c core/rdhtml.c core/rdsb.c core/rdzip.c core/rdsrc.c core/rdepub.c core/rdfb2.c core/rdmobi.c core/rdcbz.c"
+CORE_L="core/rdenc.c core/rdlayout.c core/rdtxt.c core/seg.c core/rdxml.c core/rdhtml.c core/rdsb.c core/rdzip.c core/rdsrc.c core/rdepub.c core/rdfb2.c core/rdmobi.c core/rdcbz.c"
 ENGINE_L="engine/rdft.c"
 APP_L="app.c app/shelf.c app/reader.c app/book.c app/progress.c app/settings.c app/reader_conf.c app/reader_ipc.c"
 $CC -Os -static -Wall -Wextra -I../sdk -I../meow_launcherd -I. -Icore -Iapp -Iengine $FT_INCS $COREINC \