feat(backend,frontend): tâches planifiées projet — tool MCP idea_scheduled_task_* et menu utilisateur #305, fix transcript lié indisponible après reboot #314 (QA verte)

#305: nouvel agrégat durable ScheduledProjectTask dans domain (scheduled_task.rs, ids, ports ScheduledProjectTaskStore), source de vérité <app_data_dir>/scheduled-project-tasks/<projectId>.json, schedules bornés V1 interval/daily/weekly avec fuseau, cycle À approuver/Active/Suspendue avec approbation obligatoire des tâches demandées par agent; use cases application/scheduled_task (list/create/update/delete/run_now/reconcile/fire) réutilisant BackgroundTask pour les runs avec distinction planifié/manuel; store infrastructure dédié + scheduler reconcile au boot sans rattrapage en rafale, cwd confiné au projet; 7 tools MCP idea_scheduled_task_* (list/read lecture seule, create/update/delete/run_now/set_enabled write-actions soumises aux permissions natives); commandes Tauri + routes HTTP aux contrats DTO identiques (camelCase nextRunAtMs/lastRunAtMs/lastTaskId/createdBy/updatedBy); frontend: gateways Tauri/HTTP/mock + types ports/domain, surface projet 'Tâches planifiées' (liste utilisateur+agent unifiée, création/édition avec récapitulatif avant activation, approbation/refus, exécuter maintenant, suspendre/reprendre, suppression), catalogage surface web (webSurfaceCatalog/viewPlacement/ViewPanelBody/WebWorkspace); docs/scheduled-project-tasks.md et sdk docs/services.md (047c38b: pas un service plugin V1, pas d'émulation via cron système).

#314: correction de 'Conversation liée — transcript indisponible' après reboot: restauration du transcript lié côté application (orchestrator service, lifecycle, session_limit, background sink, terminal registry) et côté frontend (adapters agent/http frames/stream/requestResponse, workStateNormalization, CustomAgentChatView avec état et action utile), tests dto_chat/agent_lifecycle/structured_registry_d1/background_completion_sink étendus.

QA verte rapportée par QA sur feature/305-scheduled-project-tasks-mcp, sans bloquant, pour #305 et #314.

Hors périmètre worktree: tickets non liés, attachments/, scripts/; aucun push.

crates/domain/src/background_task.rs

@@ -8,7 +8,7 @@ use serde::{Deserialize, Serialize};
 use thiserror::Error;
 
 use crate::conversation::ConversationId;
-use crate::ids::{AgentId, ProjectId, RendezvousId, ScheduleId, TaskId};
+use crate::ids::{AgentId, ProjectId, RendezvousId, ScheduleId, ScheduledTaskId, TaskId};
 use crate::mailbox::TicketId;
 
 /// Maximum length for human-facing task labels.
@@ -63,6 +63,26 @@ pub enum BackgroundTaskWakePolicy {
     RecordOnly,
 }
 
+/// Provenance of one concrete run.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(
+    rename_all = "camelCase",
+    rename_all_fields = "camelCase",
+    tag = "kind"
+)]
+pub enum BackgroundTaskOrigin {
+    /// Direct/manual launch or legacy task.
+    #[default]
+    Manual,
+    /// Occurrence of a durable scheduled definition.
+    Scheduled {
+        /// Durable definition that produced this run.
+        scheduled_task_id: ScheduledTaskId,
+        /// Persisted occurrence timestamp represented by this run.
+        planned_at_ms: u64,
+    },
+}
+
 /// Structural link from a background task to a composite inter-agent rendezvous.
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
@@ -137,6 +157,9 @@ pub struct BackgroundTask {
     pub state: BackgroundTaskState,
     /// Completion wake policy.
     pub wake_policy: BackgroundTaskWakePolicy,
+    /// Manual launch or scheduled occurrence provenance.
+    #[serde(default)]
+    pub origin: BackgroundTaskOrigin,
     /// Creation timestamp, epoch milliseconds.
     pub created_at_ms: u64,
     /// Last update timestamp, epoch milliseconds.
@@ -173,6 +196,7 @@ impl BackgroundTask {
             parent_task_id: None,
             state: BackgroundTaskState::Queued,
             wake_policy,
+            origin: BackgroundTaskOrigin::Manual,
             created_at_ms: now_ms,
             updated_at_ms: now_ms,
             deadline_ms,
@@ -183,6 +207,13 @@ impl BackgroundTask {
         Ok(task)
     }
 
+    /// Attaches immutable run provenance before persistence.
+    #[must_use]
+    pub fn with_origin(mut self, origin: BackgroundTaskOrigin) -> Self {
+        self.origin = origin;
+        self
+    }
+
     /// Returns a copy linked to a composite inter-agent rendezvous.
     #[must_use]
     pub fn with_rendezvous(mut self, link: BackgroundTaskRendezvousLink) -> Self {