codify "platform" into resolution logic, server-fn/fullstack overhaul (#4596)

overhaul dioxus fullstack using a new implementation of server_fn

This PR is a complete rewrite of dioxus fullstack designed to improve compatibility with axum and to fix a number of compilation errors based on feature flag unification plumbing through macros.

examples/10-integrations/bevy/src/demo_renderer.rs

@@ -0,0 +1,93 @@
+use crate::bevy_renderer::BevyRenderer;
+use crate::Color;
+use dioxus_native::{CustomPaintCtx, CustomPaintSource, DeviceHandle, TextureHandle};
+use std::sync::mpsc::{channel, Receiver, Sender};
+use wgpu::Instance;
+
+pub enum DemoMessage {
+    // Color in RGB format
+    SetColor(Color),
+}
+
+enum DemoRendererState {
+    Active(Box<BevyRenderer>),
+    Suspended,
+}
+
+pub struct DemoPaintSource {
+    state: DemoRendererState,
+    start_time: std::time::Instant,
+    tx: Sender<DemoMessage>,
+    rx: Receiver<DemoMessage>,
+    color: Color,
+}
+
+impl DemoPaintSource {
+    pub fn new() -> Self {
+        let (tx, rx) = channel();
+        Self::with_channel(tx, rx)
+    }
+
+    pub fn with_channel(tx: Sender<DemoMessage>, rx: Receiver<DemoMessage>) -> Self {
+        Self {
+            state: DemoRendererState::Suspended,
+            start_time: std::time::Instant::now(),
+            tx,
+            rx,
+            color: Color::WHITE,
+        }
+    }
+
+    pub fn sender(&self) -> Sender<DemoMessage> {
+        self.tx.clone()
+    }
+
+    fn process_messages(&mut self) {
+        loop {
+            match self.rx.try_recv() {
+                Err(_) => return,
+                Ok(msg) => match msg {
+                    DemoMessage::SetColor(color) => self.color = color,
+                },
+            }
+        }
+    }
+
+    fn render(
+        &mut self,
+        ctx: CustomPaintCtx<'_>,
+        width: u32,
+        height: u32,
+    ) -> Option<TextureHandle> {
+        if width == 0 || height == 0 {
+            return None;
+        }
+        let DemoRendererState::Active(state) = &mut self.state else {
+            return None;
+        };
+
+        state.render(ctx, self.color.components, width, height, &self.start_time)
+    }
+}
+
+impl CustomPaintSource for DemoPaintSource {
+    fn resume(&mut self, instance: &Instance, device_handle: &DeviceHandle) {
+        let active_state = BevyRenderer::new(instance, device_handle);
+        self.state = DemoRendererState::Active(Box::new(active_state));
+    }
+
+    fn suspend(&mut self) {
+        self.state = DemoRendererState::Suspended;
+    }
+
+    fn render(
+        &mut self,
+        ctx: CustomPaintCtx<'_>,
+        width: u32,
+        height: u32,
+        _scale: f64,
+    ) -> Option<TextureHandle> {
+        self.process_messages();
+        self.render(ctx, width, height)
+    }
+}