feat(domain,application,infrastructure,backend,web-server,app-tauri,frontend): lot utilisateur #325 #326 — icônes projet avec watermark CLI custom et localisation FR/EN (QA verte)

Lot en un seul commit: les deux features partagent les mêmes contrats
(domain/settings.rs, DTO, commandes Tauri/HTTP, web-server) et les mêmes
surfaces UI — la séparation par fichiers était impossible sans chirurgie
de hunks risquant des états intermédiaires non compilables (convention
lot des batches #310-#313 et #315).

#325 — icône configurable par projet, watermark CLI custom:
- domaine: ProjectIconSet (devicon, simple-icons, lucide, idea),
  ProjectIconRef validé (nom ASCII 1..=64, -_. internes), champ icon
  optionnel sur ProjectSettings; sérialisation camelCase et try_from
  strict
- application: UpdateProjectSettings.execute accepte un patch
  theme_color OU icon (absent = inchangé, null = défaut produit), tests
  in-dependants avec store mémoire
- backend/app-tauri/web-server: ProjectIconRefDto, UpdateProjectSettingsRequestDto
  avec icon optionnel (désérialisation additive), commandes
  update_project_settings alignées Tauri/HTTP, tests DTO et HTTP
  (défaut null, set, clear, nom invalide rejeté)
- frontend: catalogue projectIcons (recherche EN), ProjectIconPicker en
  grille multi-lignes dans Paramètres projet, affichage de l'icône dans
  ProjectTabs et watermark grand format à faible opacité en fond de CLI
  custom; ports ProjectSettings.icon, Partial<ProjectSettings>,
  adapters tauri/mock/http et tests alignés

#326 — localisation FR/EN et traduction des textes IdeA:
- domaine: IdeaLanguage (fr | en), champ language optionnel sur
  IdeaUserSettings (absence = défaut produit, série additive validée)
- backend/web-server: UserSettingsDto.language, update_user_settings
  accepte language, tests HTTP alignés; fixtures structured_launch_d3
  mises à jour
- frontend: i18n/ (catalogue FR/EN, I18nProvider, scan anti-régression
  des sources visibles), GeneralSettings avec sélecteur de langue dans
  les paramètres, setupI18n dans vitest; migration de l'ensemble des
  textes hardcodés vers le catalogue sur toutes les surfaces (agents,
  layout, projets, tickets, sprints, web, plugins, permissions, git,
  templates, skills, mémoire, model servers, embedder, first-run,
  devices, scheduled tasks, workstate, dialogs), FR conservé par défaut;
  recherche d'icônes #325 en anglais conformément au ticket

QA verte sur feature/batch-325-326-project-icons-localisation. Aucun push.

crates/domain/src/lib.rs

@@ -267,7 +267,10 @@ pub use scheduled_task::{
     Weekday, MIN_SCHEDULE_INTERVAL_MINUTES,
 };
 
-pub use settings::{DefaultAgentTerminalInterface, IdeaUserSettings, ProjectSettings, ThemeColor};
+pub use settings::{
+    DefaultAgentTerminalInterface, IdeaLanguage, IdeaUserSettings, ProjectIconRef, ProjectIconSet,
+    ProjectSettings, ThemeColor, MAX_PROJECT_ICON_NAME_LEN,
+};
 
 pub use orchestrator::{
     OrchestratorCommand, OrchestratorError, OrchestratorRequest, OrchestratorVisibility,

crates/domain/src/settings.rs

@@ -12,6 +12,16 @@ pub enum DefaultAgentTerminalInterface {
     IdeaCli,
 }
 
+/// User-selected IdeA interface language.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum IdeaLanguage {
+    /// French interface.
+    Fr,
+    /// English interface.
+    En,
+}
+
 /// Global, machine-local IdeA preferences.
 #[derive(Debug, Clone, Default, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
@@ -19,6 +29,83 @@ pub struct IdeaUserSettings {
     /// Default for newly launched human-facing agent terminals.
     #[serde(default)]
     pub default_agent_terminal_interface: Option<DefaultAgentTerminalInterface>,
+    /// Preferred interface language. Absence preserves the product default.
+    #[serde(default)]
+    pub language: Option<IdeaLanguage>,
+}
+
+/// Supported icon catalogue for project visual identity.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub enum ProjectIconSet {
+    /// Devicon language and platform catalogue.
+    Devicon,
+    /// Simple Icons brand catalogue.
+    SimpleIcons,
+    /// Lucide general-purpose icon catalogue.
+    Lucide,
+    /// IdeA-owned built-in icons.
+    Idea,
+}
+
+/// Maximum byte length of a stable project icon name.
+pub const MAX_PROJECT_ICON_NAME_LEN: usize = 64;
+
+/// Validated reference to one icon in a known catalogue.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase", try_from = "UncheckedProjectIconRef")]
+pub struct ProjectIconRef {
+    set: ProjectIconSet,
+    name: String,
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct UncheckedProjectIconRef {
+    set: ProjectIconSet,
+    name: String,
+}
+
+impl ProjectIconRef {
+    /// Builds a validated stable icon reference.
+    pub fn new(set: ProjectIconSet, name: impl Into<String>) -> Result<Self, String> {
+        let name = name.into();
+        let bytes = name.as_bytes();
+        let valid_name = !name.is_empty()
+            && name.len() <= MAX_PROJECT_ICON_NAME_LEN
+            && bytes.first().is_some_and(u8::is_ascii_alphanumeric)
+            && bytes.last().is_some_and(u8::is_ascii_alphanumeric)
+            && bytes
+                .iter()
+                .copied()
+                .all(|byte| byte.is_ascii_alphanumeric() || matches!(byte, b'-' | b'_' | b'.'));
+        if !valid_name {
+            return Err(format!(
+                "project icon name must be 1..={MAX_PROJECT_ICON_NAME_LEN} ASCII letters, digits, '-', '_' or '.', starting and ending with a letter or digit"
+            ));
+        }
+        Ok(Self { set, name })
+    }
+
+    /// Returns the owning icon catalogue.
+    #[must_use]
+    pub const fn set(&self) -> ProjectIconSet {
+        self.set
+    }
+
+    /// Returns the stable catalogue icon name.
+    #[must_use]
+    pub fn name(&self) -> &str {
+        &self.name
+    }
+}
+
+impl TryFrom<UncheckedProjectIconRef> for ProjectIconRef {
+    type Error = String;
+
+    fn try_from(value: UncheckedProjectIconRef) -> Result<Self, Self::Error> {
+        Self::new(value.set, value.name)
+    }
 }
 
 /// Strict project theme colour (`#RRGGBB`).
@@ -66,4 +153,7 @@ pub struct ProjectSettings {
     /// Optional visual theme colour; absence keeps the product fallback.
     #[serde(default)]
     pub theme_color: Option<ThemeColor>,
+    /// Optional validated icon used as the project's visual identity.
+    #[serde(default)]
+    pub icon: Option<ProjectIconRef>,
 }