refactor(config,audio): merge config into oakcommon, split oakaudio

- config moves into oakcommon as ConfigStore + oakcommon_config_* C
  API (INI storage, typed entries, error-handler injection); node and
  render call sites keep OAK_CONFIG() macro shape via a local shim
  that forwards to the C API; transition config stubs removed
- oakaudio: de-Qt all six classes, C ABI in include/audio with
  refcounted handles (processor/manager/waveform/levelmeter/sync,
  48 functions); PreviewAudioDevice moved in from render; recording
  goes through oakcodec encoder; waveform extract uses probe +
  ffmpeg_bridge decode (decode_audio needs M8 task system)
- fix re_sum_samples min/max init bug (values clamped to 0 for
  same-sign ranges)
- every C API function has positive + error-path tests; suites:
  oakcommon 193, oakaudio 36, oaknode 96, oakrender 42, oakcodec 18

src/render/transition/config/config.h

@@ -1,43 +0,0 @@
-#pragma once
-// Transitional stub for engine/config/config.h (still Qt-based, config 未拆分).
-// Union of the src/node/transition stub and the render-facing surface:
-// keeps the OAK_CONFIG* call shape; values are inert defaults until the
-// config milestone wires the real store. operator[] returns a stored
-// reference so writes (lutlibrary) compile; nothing is persisted. 只增不删。
-#include <map>
-#include <string>
-#include "variant.h"
-#ifndef QStringLiteral
-#define QStringLiteral(x) x
-#endif
-namespace olive {
-class ConfigValue : public olive::Variant {
-public:
-	ConfigValue() = default;
-	ConfigValue(const std::string &s) : olive::Variant(s) {}
-	ConfigValue &operator=(const std::string &s)
-	{
-		olive::Variant::operator=(olive::Variant(s));
-		return *this;
-	}
-	bool toBool() const { return to_bool(); }
-	int toInt() const { return to_int(); }
-	uint64_t toULongLong() const { return to_u_long_long(); }
-	// rendermanager reads the graphics backend name through this
-	std::string toString() const { return to_string(); }
-	std::vector<std::string> toStringList() const { return to_string_list(); }
-};
-class Config {
-public:
-	static Config &current() { static Config c; return c; }
-	ConfigValue &operator[](const std::string &key) { return values_[key]; }
-private:
-	std::map<std::string, ConfigValue> values_;
-};
-}
-#ifndef OAK_CONFIG
-#define OAK_CONFIG(x) Config::current()[x]
-#endif
-#ifndef OAK_CONFIG_STR
-#define OAK_CONFIG_STR(x) Config::current()[x]
-#endif