feat(gst): enhance GStreamer integration with new modules and improved API

This commit introduces significant enhancements to the GStreamer integration by:
- Adding new modules for bins, caps, elements, pads, and plugins
- Implementing a more ergonomic API with helper methods like play(), pause(), ready()
- Adding support for various GStreamer plugins including app, autodetect, playback, and videoconvertscale
- Improving error handling with better context attachment
- Updating dependencies to latest versions including gstreamer-video 0.24.4
- Refactoring existing code to use modern Rust patterns and features

gst/src/caps.rs

@@ -0,0 +1,53 @@
+use crate::*;
+#[repr(transparent)]
+pub struct Caps {
+    pub(crate) inner: gstreamer::caps::Caps,
+}
+
+impl Caps {
+    pub fn builder(cs: CapsType) -> CapsBuilder {
+        CapsBuilder::new(cs)
+    }
+}
+
+pub struct CapsBuilder {
+    inner: gstreamer::caps::Builder<gstreamer::caps::NoFeature>,
+}
+
+impl CapsBuilder {
+    pub fn field<V: Into<glib::Value> + Send>(mut self, name: impl AsRef<str>, value: V) -> Self {
+        use gstreamer::prelude::*;
+        self.inner = self.inner.field(name.as_ref(), value);
+        self
+    }
+
+    pub fn build(self) -> Caps {
+        Caps {
+            inner: self.inner.build(),
+        }
+    }
+}
+
+pub enum CapsType {
+    Video,
+    Audio,
+    Text,
+}
+
+impl CapsType {
+    pub fn as_str(&self) -> &str {
+        match self {
+            CapsType::Video => "video/x-raw",
+            CapsType::Audio => "audio/x-raw",
+            CapsType::Text => "text/x-raw",
+        }
+    }
+}
+
+impl CapsBuilder {
+    pub fn new(cs: CapsType) -> Self {
+        CapsBuilder {
+            inner: gstreamer::Caps::builder(cs.as_str()),
+        }
+    }
+}