feat(build): 实现 Qt 运行时依赖部署（runtime.qt6_path / qt6_dlls / qt6_plugins）

背景：project.vpj 里的 runtime 块此前只是声明（编译器不读取），Qr 程序运行时报 Could not find the Qt platform plugin "windows"。

实现：链接成功后（Phase2 的 PhaseC 成功点）调用 BuildPipeline.deploy_runtime_deps(exe_path)——把 qt6_dlls 各项从 <qt6_path>/bin 复制到 exe 同目录；把新增的可选字段 qt6_plugins 各项从 <qt6_path>/plugins 复制到 <exe 目录>/<相对路径>（父目录不存在则 mkdir）。Config.vp 新增 Qt6Path/Qt6Dlls/Qt6Plugins 读取（口径同 LinkerStaticLibs）。

fail-fast：声明了但源文件不存在 / 复制失败 / mkdir 失败 => VLogger.error 并中止构建；三字段全未声明则整段跳过。

验证：重编 SUCCESS（210.11s）；ViperMNIST 产物含 7 个 Qt6*.dll + platforms/qwindows.dll，实跑 stderr 无插件报错；ViperAIChat / ViperQtHelloWorld 同样 OK 并完成部署。

App/lib/Phase/BuildPipeline.vp

@@ -15,6 +15,8 @@ import w32.win32sync as win32sync
 import subprocess
 import viperlib
 import ast
+import os as oslib
+import shutil
 import lib.core.VLogger as VLogger
 import lib.core.Gen.Translator as HandlesTranslator
 import lib.core.Gen.DebugInfoGen as DebugInfoGen
@@ -2399,4 +2401,122 @@ def run_pipeline(ir_buf: bytes, ir_len: sizet, temp_dir: str, output_dir: str, m
         return result
 
     result.Success = 1
-    return result
+    return result
+
+
+# =============================================================================
+# Runtime dependency deployment (project.vpj runtime.*)
+# After a successful link, copy the declared runtime deps next to the exe.
+# Optional: no-op unless runtime.qt6_path / qt6_dlls / qt6_plugins are declared.
+# Fail-fast: a declared source that is missing, or a failed copy/dir-create, aborts the build.
+# =============================================================================
+
+def _deploy_dir_of(path: str) -> str:
+    """Return the directory portion of path (text before the last / or backslash); None if no separator."""
+    if path is None: return None
+    plen: sizet = string.strlen(path)
+    i: sizet = plen
+    while i > 0:
+        if path[i - 1] == '/' or path[i - 1] == '\\': break
+        i -= 1
+    if i == 0: return None
+    buf: str = _mbuddy.alloc(i)
+    if buf is None: return None
+    string.strncpy(buf, path, i - 1)
+    buf[i - 1] = '\0'
+    return buf
+
+
+def _deploy_join(base: str, name: str) -> str:
+    """Join base and name with '/'; mbuddy-allocated."""
+    if base is None or name is None: return None
+    bl: sizet = string.strlen(base)
+    nl: sizet = string.strlen(name)
+    buf: str = _mbuddy.alloc(bl + nl + 2)
+    if buf is None: return None
+    viperlib.snprintf(buf, bl + nl + 2, "%s/%s", base, name)
+    return buf
+
+
+def _deploy_token(s: str, start: sizet, end: sizet) -> str:
+    """Copy s[start:end] into an mbuddy-allocated NUL-terminated string; None on OOM."""
+    n: sizet = end - start
+    buf: str = _mbuddy.alloc(n + 1)
+    if buf is None: return None
+    string.strncpy(buf, s + start, n)
+    buf[n] = '\0'
+    return buf
+
+
+def deploy_runtime_deps(exe_path: str) -> int:
+    """Deploy declared runtime dependencies (project.vpj runtime.*) next to the exe; 0=ok, 1=fail.
+    No-op when runtime.qt6_path / qt6_dlls / qt6_plugins are undeclared. Fail-fast otherwise."""
+    if exe_path is None: return 0
+    qt6_path: str = Config.Qt6Path
+    if qt6_path is None: return 0
+    dlls: str = Config.Qt6Dlls
+    plugins: str = Config.Qt6Plugins
+    if dlls is None and plugins is None: return 0
+
+    exe_dir: str = _deploy_dir_of(exe_path)
+    if exe_dir is None:
+        VLogger.error(f"runtime deploy: cannot determine exe directory from {exe_path}", "runtime")
+        return 1
+    bin_dir: str = _deploy_join(qt6_path, "bin")
+    plug_root: str = _deploy_join(qt6_path, "plugins")
+
+    # runtime.qt6_dlls: <qt6_path>/bin/<dll> -> <exe_dir>/<dll>
+    if dlls is not None:
+        total: sizet = string.strlen(dlls)
+        i: sizet = 0
+        while i < total:
+            while i < total and dlls[i] == ' ': i += 1
+            if i >= total: break
+            start: sizet = i
+            while i < total and dlls[i] != ' ': i += 1
+            if i > start:
+                name: str = _deploy_token(dlls, start, i)
+                if name is None:
+                    VLogger.error("runtime deploy: DLL name allocation failed (OOM)", "runtime")
+                    return 1
+                src: str = _deploy_join(bin_dir, name)
+                dst: str = _deploy_join(exe_dir, name)
+                if not oslib.isfile(src):
+                    VLogger.error(f"runtime deploy: declared DLL not found: {src}", "runtime")
+                    return 1
+                if shutil.copyfile(src, dst) != 0:
+                    VLogger.error(f"runtime deploy: failed to copy {src} -> {dst}", "runtime")
+                    return 1
+                VLogger.info(f"runtime deploy: {name}", "runtime")
+
+    # runtime.qt6_plugins: <qt6_path>/plugins/<rel> -> <exe_dir>/<rel> (ensure parent dir)
+    if plugins is not None:
+        total_p: sizet = string.strlen(plugins)
+        ip: sizet = 0
+        while ip < total_p:
+            while ip < total_p and plugins[ip] == ' ': ip += 1
+            if ip >= total_p: break
+            start_p: sizet = ip
+            while ip < total_p and plugins[ip] != ' ': ip += 1
+            if ip > start_p:
+                rel: str = _deploy_token(plugins, start_p, ip)
+                if rel is None:
+                    VLogger.error("runtime deploy: plugin path allocation failed (OOM)", "runtime")
+                    return 1
+                src_p: str = _deploy_join(plug_root, rel)
+                dst_p: str = _deploy_join(exe_dir, rel)
+                parent: str = _deploy_dir_of(dst_p)
+                if parent is not None:
+                    if not oslib.isdir(parent):
+                        if oslib.mkdir(parent) != 0:
+                            VLogger.error(f"runtime deploy: failed to create dir {parent}", "runtime")
+                            return 1
+                if not oslib.isfile(src_p):
+                    VLogger.error(f"runtime deploy: declared plugin not found: {src_p}", "runtime")
+                    return 1
+                if shutil.copyfile(src_p, dst_p) != 0:
+                    VLogger.error(f"runtime deploy: failed to copy {src_p} -> {dst_p}", "runtime")
+                    return 1
+                VLogger.info(f"runtime deploy: {rel}", "runtime")
+
+    return 0

App/lib/Phase/Phase2/__init__.vp

@@ -1506,6 +1506,14 @@ def RunMultiFileProject(mb: memhub.MemBuddy*, source_dir: str, temp_dir: str, ou
 
         if lret == 0:
             VLogger.success(f"output: {exe_path}", "PhaseC")
+            # Deploy declared runtime deps (project.vpj runtime.*) next to the exe; fail-fast on error.
+            # Skipped under --phase2command (the exe is not linked yet).
+            if BuildPipeline._phase2_cmd_path is None:
+                if BuildPipeline.deploy_runtime_deps(exe_path) != 0:
+                    VLogger.error("runtime dependency deployment failed, aborting compilation", "runtime")
+                    stdlib.free(entries)
+                    stdlib.free(asm_entries)
+                    return 1
             # --traceback: export <exe>.stackmap (skipped under --phase2command,
             # where nothing was actually linked).
             if BuildPipeline._traceback_mode != 0 and BuildPipeline._phase2_cmd_path is None: BuildPipeline.WriteStackMap(mb, exe_path)