feat(plugins): paramètres projet plugins + attribution skills/tools aux agents — #282 (manifeste accepte contributes.skills IdeA-native multi-harness; store .ideai/project-plugins.json v1: enable plugin par projet + assignments skills/tools par agent; refs + use cases settings/assign/unassign; resolver skills pour idea_skill_read et injection catalogue lancement agent; permissions MCP dynamiques projetées par harness Claude Code/Codex/OpenCode; tombstones uninstall, hot reload recalcule catalogue et marque assignments cassés; frontend: Settings projet Plugins, détail capabilities, attribution agent, catalogue permissions; bump pointeur IdeaSDK 6eb8db3; QA verte: cargo test -p application, project_plugin_settings 3/3, dto_plugins 2/2, structured_launch_d3 26/26, catalogue mcp 7/7, frontend 5 tests ProjectPluginSettings/plugin, npm build frontend)

crates/domain/src/ports.rs

@@ -446,6 +446,19 @@ pub trait PluginPackageStore: Send + Sync {
         package: &PluginPackageRef,
     ) -> Result<PluginManifestBytes, PluginStoreError>;
 
+    /// Reads a package-relative file from an installed plugin, confined to its
+    /// canonical package root.
+    async fn read_installed_file(
+        &self,
+        plugin_id: &crate::PluginId,
+        path: &crate::RelativePath,
+    ) -> Result<Vec<u8>, PluginStoreError> {
+        let _ = (plugin_id, path);
+        Err(PluginStoreError::Invalid(
+            "installed package file reads are not supported by this adapter".to_owned(),
+        ))
+    }
+
     /// Stages an archive for validation.
     async fn install_from_archive(
         &self,
@@ -496,6 +509,23 @@ pub trait PluginRegistryStore: Send + Sync {
     async fn save_registry(&self, registry: &PluginRegistry) -> Result<(), PluginRegistryError>;
 }
 
+/// Store for one project's plugin activation and agent assignments.
+#[async_trait]
+pub trait ProjectPluginSettingsStore: Send + Sync {
+    /// Loads settings, returning an empty version-1 document when missing.
+    async fn load(
+        &self,
+        project_root: &crate::ProjectPath,
+    ) -> Result<crate::ProjectPluginSettings, StoreError>;
+
+    /// Atomically persists the complete document.
+    async fn save(
+        &self,
+        project_root: &crate::ProjectPath,
+        settings: &crate::ProjectPluginSettings,
+    ) -> Result<(), StoreError>;
+}
+
 /// Manifest parser and validator.
 pub trait PluginManifestValidator: Send + Sync {
     /// Validates raw manifest bytes.