feat(capture): add Phase 3 PipeWire capture stub and config string safety

Add a linkable CaptureFactory stub so the capture API can be consumed

without unresolved symbols. Change remaining config string_view fields to

std::string to prevent dangling references. Update handoff memory.

include/screencast/render/renderer.h

@@ -2,36 +2,34 @@
 
 #include "screencast/codec/decoder.h"
 
-#include <cstdint>
 #include <memory>
-#include <optional>
-#include <string_view>
+#include <string>
 
 namespace sc {
 
 struct RendererConfig {
-    std::string_view window_title = "screencast receiver";
+    std::string window_title = "screencast receiver";
     int initial_width = 1280;
     int initial_height = 720;
 };
 
 class Renderer {
   public:
-    virtual ~Renderer () = default;
+    virtual ~Renderer() = default;
 
     // Present one decoded frame. Returns false if the window was closed.
-    virtual bool present ( const DecodedFrame &frame ) = 0;
+    virtual bool present(const DecodedFrame& frame) = 0;
 
     // Pump events (window close, resize). Non-blocking.
-    virtual bool poll_events () = 0;
+    virtual bool poll_events() = 0;
 
     // Destroy the window and release GPU resources.
-    virtual void shutdown () = 0;
+    virtual void shutdown() = 0;
 };
 
 class RendererFactory {
   public:
-    static std::unique_ptr<Renderer> create ( const RendererConfig &config );
+    static std::unique_ptr<Renderer> create(const RendererConfig& config);
 };
 
-}  // namespace sc
+} // namespace sc