personas: elevate to server with per-persona fact scoping

Move personas off the mobile client into ImageApi as first-class
records, and scope entity_facts by persona so each one builds its own
voice over a shared entity graph. The new include_all_memories flag
lets a persona opt back into the full hive-mind pool for human
browsing of /knowledge/*; agentic generation always stays in-voice.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/database/models.rs

@@ -1,6 +1,6 @@
 use crate::database::schema::{
-    entities, entity_facts, entity_photo_links, favorites, image_exif, libraries, photo_insights,
-    users, video_preview_clips,
+    entities, entity_facts, entity_photo_links, favorites, image_exif, libraries, personas,
+    photo_insights, users, video_preview_clips,
 };
 use serde::Serialize;
 
@@ -238,6 +238,11 @@ pub struct InsertEntityFact {
     pub confidence: f32,
     pub status: String,
     pub created_at: i64,
+    /// Which persona authored this fact. Shared entities, persona-tagged
+    /// facts: each persona accumulates its own voice over the same
+    /// real-world referents. Defaults to `'default'` for legacy rows
+    /// (see migration 2026-05-09-000000).
+    pub persona_id: String,
 }
 
 #[derive(Serialize, Queryable, Clone, Debug)]
@@ -252,6 +257,7 @@ pub struct EntityFact {
     pub confidence: f32,
     pub status: String,
     pub created_at: i64,
+    pub persona_id: String,
 }
 
 #[derive(Insertable)]
@@ -274,6 +280,34 @@ pub struct EntityPhotoLink {
     pub role: String,
 }
 
+// --- Personas ---
+
+#[derive(Insertable)]
+#[diesel(table_name = personas)]
+pub struct InsertPersona<'a> {
+    pub user_id: i32,
+    pub persona_id: &'a str,
+    pub name: &'a str,
+    pub system_prompt: &'a str,
+    pub is_built_in: bool,
+    pub include_all_memories: bool,
+    pub created_at: i64,
+    pub updated_at: i64,
+}
+
+#[derive(Serialize, Queryable, Clone, Debug)]
+pub struct Persona {
+    pub id: i32,
+    pub user_id: i32,
+    pub persona_id: String,
+    pub name: String,
+    pub system_prompt: String,
+    pub is_built_in: bool,
+    pub include_all_memories: bool,
+    pub created_at: i64,
+    pub updated_at: i64,
+}
+
 #[derive(Insertable)]
 #[diesel(table_name = video_preview_clips)]
 pub struct InsertVideoPreviewClip {