chore(test): 初始化回归测试仓（新增 .gitignore，TestsOverview.md 改为 README.md）

把 Test/ 纳入 https://git.gvsds.com/GVSDS/Viper_RegressionTesting 。

1) 新增 .gitignore —— 只保留测试源码，剔除全部构建产物：
   目录   **/output*/（output / output_opt / output_orig / output_verify / output_dbg）、
          **/temp*/（temp / temp_opt）、**/.tpv_build/
   二进制 *.exe *.obj *.o *.out *.a *.lib *.dll
   中间物 *.ll *.vpi *.pyi *.deps.txt *.deps.json *.doc.json *_sha1_map.txt
          _pyi_cache_v1.pkl _pyi_cache_v1.sig.json _shared_sym.json _phase1_manifest.json
   其它   build_all.txt（构建日志）、*.log、__pycache__/、*.bak、IDE 目录
   保留   App/*.vp、project.json / project_opt.json / project.vpj、README.md、两个 .py
   实测 `git add -A --dry-run`：196 个文件，无任何构建产物混入。

2) TestsOverview.md → README.md（作为仓库首页文档）。

3) SequentialRegressionTest.py：7 处 TestsOverview.md 引用同步改为 README.md
   （文档串、OVERVIEW 路径、read_test_order 文档与报错文案、argparse description、
   启动横幅）；同时修正入口路径 PROJECTRANS —— 旧值 <root>/Projectrans.py 已不存在，
   改为 <root>/TransPyC/Projectrans.py（与 regression_test.py:45-48 记录一致），
   否则本脚本会以 "can't open file" 全量失败。
   regression_test.py 无需改动：它按目录扫描 project.json 找项目，不引用该文档。

EnumTest/App/enumtest.vp

@@ -0,0 +1,95 @@
+import t, c
+from t import CInt, CPtr, CChar, CInt32T, CExport
+import viperlib
+import stdlib
+
+
+class Color(t.CEnum):
+    Red = 0
+    Green = 1
+    Blue = 2
+
+
+class Option(t.REnum):
+    class Some:
+        value: CInt
+    Empty = 1
+
+
+class Result(t.REnum):
+    class Ok:
+        value: CInt
+    class Err:
+        msg: t.CChar | CPtr
+
+
+class GeoShape(t.REnum):
+    class GCircle:
+        radius: CInt
+    class GRect:
+        w: CInt
+        h: CInt
+    class GPoint:
+        x: CInt
+        y: CInt
+
+
+def enum_main() -> CInt:
+    buf: CChar | CPtr = CPtr(stdlib.malloc(256))
+
+    c1: CInt = Color.Red
+    c2: CInt = Color.Green
+    c3: CInt = Color.Blue
+    viperlib.snprintf(buf, 256, "CEnum: Red=%d Green=%d Blue=%d", c1, c2, c3)
+    print(buf)
+
+    opt: Option = Option.Some(42)
+    match opt:
+        case Option.Some(v):
+            viperlib.snprintf(buf, 256, "Option.Some: value=%d", v)
+            print(buf)
+        case Option.Empty():
+            pass
+
+    res1: Result = Result.Ok(100)
+    match res1:
+        case Result.Ok(v):
+            viperlib.snprintf(buf, 256, "Result.Ok: value=%d", v)
+            print(buf)
+        case Result.Err(e):
+            pass
+
+    res2: Result = Result.Err("not found")
+    match res2:
+        case Result.Ok(v):
+            pass
+        case Result.Err(e):
+            viperlib.snprintf(buf, 256, "Result.Err: msg=%s", e)
+            print(buf)
+
+    s1: GeoShape = GeoShape.GCircle(5)
+    match s1:
+        case GeoShape.GCircle(r):
+            viperlib.snprintf(buf, 256, "GeoShape.GCircle: radius=%d", r)
+            print(buf)
+        case _:
+            pass
+
+    s2: GeoShape = GeoShape.GRect(10, 20)
+    match s2:
+        case GeoShape.GRect(w, h):
+            viperlib.snprintf(buf, 256, "GeoShape.GRect: w=%d h=%d", w, h)
+            print(buf)
+        case _:
+            pass
+
+    s3: GeoShape = GeoShape.GPoint(3, 4)
+    match s3:
+        case GeoShape.GPoint(x, y):
+            viperlib.snprintf(buf, 256, "GeoShape.GPoint: x=%d y=%d", x, y)
+            print(buf)
+        case _:
+            pass
+
+    stdlib.free(buf)
+    return 0

EnumTest/App/main.vp

@@ -0,0 +1,11 @@
+import t, c
+import testcheck
+import enumtest
+
+
+def main() -> t.CInt | t.CExport:
+    testcheck.begin("EnumTest: 枚举类型测试")
+    testcheck.section("Enum")
+    enumtest.enum_main()
+    testcheck.ok("Enum 测试完成")
+    return testcheck.end()