feat(windows): persistance et restauration des fenêtres au redémarrage (#40)

Persiste l'état des fenêtres (layout/position) et le restaure au
relancement de l'application. Découpage hexagonal :
- domaine : modèle et port d'état des fenêtres (layout, ports)
- application : use cases de persistance/restauration
- infrastructure : store window_state (adapter de persistance)
- présentation : câblage app-tauri (state, commands, lib)
Couvert par des tests ciblés domaine/application/infrastructure.

Depend de #39 (fermeture des fenêtres auxiliaires).

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

crates/app-tauri/src/commands.rs

@@ -2341,7 +2341,7 @@ pub struct ViewWindowLifecycleEventDto {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
-enum ViewPanel {
+pub(crate) enum ViewPanel {
     Projects,
     Context,
     Work,
@@ -2355,7 +2355,7 @@ enum ViewPanel {
 }
 
 impl ViewPanel {
-    fn parse(raw: &str) -> Result<Self, ErrorDto> {
+    pub(crate) fn parse(raw: &str) -> Result<Self, ErrorDto> {
         match raw {
             "projects" => Ok(Self::Projects),
             "context" => Ok(Self::Context),
@@ -2374,7 +2374,7 @@ impl ViewPanel {
         }
     }
 
-    const fn as_str(self) -> &'static str {
+    pub(crate) const fn as_str(self) -> &'static str {
         match self {
             Self::Projects => "projects",
             Self::Context => "context",
@@ -2389,7 +2389,7 @@ impl ViewPanel {
         }
     }
 
-    const fn title(self) -> &'static str {
+    pub(crate) const fn title(self) -> &'static str {
         match self {
             Self::Projects => "Projects",
             Self::Context => "Project context",
@@ -2405,15 +2405,15 @@ impl ViewPanel {
     }
 }
 
-fn view_window_label(panel: ViewPanel, project_id: domain::ProjectId) -> String {
+pub(crate) fn view_window_label(panel: ViewPanel, project_id: domain::ProjectId) -> String {
     format!("view-{}-{}", panel.as_str(), project_id.as_uuid().simple())
 }
 
-fn view_window_url(panel: ViewPanel, project_id: domain::ProjectId) -> String {
+pub(crate) fn view_window_url(panel: ViewPanel, project_id: domain::ProjectId) -> String {
     format!("index.html?panel={}&project={}", panel.as_str(), project_id)
 }
 
-fn emit_view_window_lifecycle(
+pub(crate) fn emit_view_window_lifecycle(
     app: &AppHandle,
     kind: &'static str,
     panel: ViewPanel,