feat(wave): #119/#122/#131/#132 verts + sprint plugins ESM/persistance #135/#136/#139

État d'intégration confiné à la branche batch. Les tickets #119 (skills →
capacités agent découvrables), #122 (override permissions par défaut), #131
(effort par agent/presets) et #132 (outil MCP d'édition du contexte projet)
sont verts en périmètre. Le sprint plugins multi-fichiers ESM / persistance
plugin-owned (#135/#136/#139) est co-implémenté dans les MÊMES fichiers de
câblage (frontend/src/ports/index.ts, backend/src/lib.rs, domain/ports.rs,
backend/dto.rs), inséparable sans staging interactif (indisponible ici).

Commit unique volontaire : préserve l'état vert QA sans découpe hunk risquée.
NON mergé vers develop tant que #137 (QA e2e plugins) n'est pas vert.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/app-tauri/src/plugins.rs

@@ -10,11 +10,11 @@ use backend::dto::{
     PluginEventPollDto, PluginEventSubscribeDto, PluginEventSubscriptionDto,
     PluginEventUnsubscribeDto, PluginInstallResultDto, PluginProjectStructureDto,
     PluginProjectStructureQueryDto, PluginReviewDto, PluginRunCommandDto,
-    PluginRuntimeContributionCatalogDto, PluginTaskDto, PluginTaskStatusDto,
-    PluginToolchainDiagnosticDto, PluginToolchainDiagnosticRequestDto, PluginUninstallResultDto,
-    PluginWorkspaceBinaryFileDto, PluginWorkspaceDirectoryListingDto, PluginWorkspacePathDto,
-    PluginWorkspaceStatDto, PluginWorkspaceTextFileDto, PluginWorkspaceWriteBinaryDto,
-    PluginWorkspaceWriteTextDto, ReviewPluginPackageDto,
+    PluginRuntimeContributionCatalogDto, PluginStorageGetDto, PluginStorageSetDto, PluginTaskDto,
+    PluginTaskStatusDto, PluginToolchainDiagnosticDto, PluginToolchainDiagnosticRequestDto,
+    PluginUninstallResultDto, PluginWorkspaceBinaryFileDto, PluginWorkspaceDirectoryListingDto,
+    PluginWorkspacePathDto, PluginWorkspaceStatDto, PluginWorkspaceTextFileDto,
+    PluginWorkspaceWriteBinaryDto, PluginWorkspaceWriteTextDto, ReviewPluginPackageDto,
 };
 use domain::ports::{PluginManifestValidator, PluginPackageStore, PluginRegistryStore};
 use domain::{PluginId, RelativePath};
@@ -216,6 +216,45 @@ pub async fn plugin_workspace_write_binary(
         .map_err(ErrorDto::from)
 }
 
+/// Reads a plugin-owned JSON storage value.
+#[tauri::command]
+pub async fn plugin_storage_get(
+    input: PluginStorageGetDto,
+    state: State<'_, AppState>,
+) -> Result<Option<serde_json::Value>, ErrorDto> {
+    state
+        .plugin_storage_access
+        .get(input.into())
+        .await
+        .map_err(ErrorDto::from)
+}
+
+/// Writes a plugin-owned JSON storage value.
+#[tauri::command]
+pub async fn plugin_storage_set(
+    input: PluginStorageSetDto,
+    state: State<'_, AppState>,
+) -> Result<(), ErrorDto> {
+    state
+        .plugin_storage_access
+        .set(input.into())
+        .await
+        .map_err(ErrorDto::from)
+}
+
+/// Deletes a plugin-owned JSON storage value.
+#[tauri::command]
+pub async fn plugin_storage_delete(
+    input: PluginStorageGetDto,
+    state: State<'_, AppState>,
+) -> Result<bool, ErrorDto> {
+    state
+        .plugin_storage_access
+        .delete(input.into())
+        .await
+        .map_err(ErrorDto::from)
+}
+
 /// Lists a workspace directory for the public plugin API.
 #[tauri::command]
 pub async fn plugin_workspace_list_dir(