feat: implement FParkan architecture foundation

Add the modular fparkan workspace, domain crates, adapters, apps, xtask policy/CI, acceptance evidence, and licensed corpus gates for the macOS-focused roadmap foundation.

adapters/fparkan-platform-sdl/src/lib.rs

@@ -0,0 +1,123 @@
+#![forbid(unsafe_code)]
+//! SDL platform adapter proof behind safe `FParkan` ports.
+
+use fparkan_platform::{
+    EventSource, GraphicsContextRequest, GraphicsProfile, PhysicalSize, PlatformError,
+    PlatformEvent, Version, WindowPort,
+};
+
+/// Adapter capabilities compiled into this package.
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct SdlAdapterCapabilities {
+    /// Supported graphics context requests in preference order.
+    pub graphics: Vec<GraphicsContextRequest>,
+    /// Whether adapter-owned code is free of `unsafe`.
+    pub project_owned_unsafe_free: bool,
+}
+
+impl Default for SdlAdapterCapabilities {
+    fn default() -> Self {
+        Self {
+            graphics: vec![
+                GraphicsContextRequest {
+                    profile: GraphicsProfile::DesktopCore,
+                    version: Version { major: 3, minor: 3 },
+                },
+                GraphicsContextRequest {
+                    profile: GraphicsProfile::Embedded,
+                    version: Version { major: 2, minor: 0 },
+                },
+            ],
+            project_owned_unsafe_free: true,
+        }
+    }
+}
+
+/// Returns adapter readiness status for the safe project-owned layer.
+#[must_use]
+pub fn safe_adapter_ready() -> bool {
+    SdlAdapterCapabilities::default().project_owned_unsafe_free
+}
+
+/// In-memory event source used by adapter smoke tests and composition roots
+/// before a concrete SDL runtime is injected.
+#[derive(Clone, Debug, Default)]
+pub struct SdlEventSourceProof {
+    pending: Vec<PlatformEvent>,
+}
+
+impl SdlEventSourceProof {
+    /// Creates an event source with deterministic pending events.
+    #[must_use]
+    pub fn new(pending: Vec<PlatformEvent>) -> Self {
+        Self { pending }
+    }
+}
+
+impl EventSource for SdlEventSourceProof {
+    fn poll(&mut self, out: &mut Vec<PlatformEvent>) -> Result<(), PlatformError> {
+        out.append(&mut self.pending);
+        Ok(())
+    }
+}
+
+/// Safe window-port proof with SDL-compatible drawable-size semantics.
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct SdlWindowProof {
+    size: PhysicalSize,
+    presents: u64,
+}
+
+impl SdlWindowProof {
+    /// Creates a proof window with a fixed drawable size.
+    #[must_use]
+    pub fn new(size: PhysicalSize) -> Self {
+        Self { size, presents: 0 }
+    }
+
+    /// Number of successful present calls.
+    #[must_use]
+    pub fn presents(&self) -> u64 {
+        self.presents
+    }
+}
+
+impl WindowPort for SdlWindowProof {
+    fn drawable_size(&self) -> PhysicalSize {
+        self.size
+    }
+
+    fn present(&mut self) -> Result<(), PlatformError> {
+        self.presents = self.presents.saturating_add(1);
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn adapter_reports_safe_project_layer_ready() {
+        assert!(safe_adapter_ready());
+        assert_eq!(SdlAdapterCapabilities::default().graphics.len(), 2);
+    }
+
+    #[test]
+    fn event_source_and_window_ports_are_deterministic() -> Result<(), PlatformError> {
+        let mut source = SdlEventSourceProof::new(vec![PlatformEvent::Quit]);
+        let mut events = Vec::new();
+        source.poll(&mut events)?;
+        source.poll(&mut events)?;
+        assert_eq!(events, vec![PlatformEvent::Quit]);
+
+        let mut window = SdlWindowProof::new(PhysicalSize {
+            width: 320,
+            height: 240,
+        });
+        assert_eq!(window.drawable_size().width, 320);
+        window.present()?;
+        assert_eq!(window.presents(), 1);
+        Ok(())
+    }
+}