feat: Organizations + Invitations routes migrated to Rust

- New migration: organizations, organization_members, invitations tables
- New model: Organization, OrganizationMember, Invitation
- Full CRUD: list/create/get/update orgs, members, invitations
- Public invitation lookup + accept flow
- JWT auth for all protected endpoints
- Admin role verification for org management
- 18/18 tests pass

boosapi-rs/src/db/models/mod.rs

@@ -8,5 +8,6 @@ pub mod setting;
 pub mod site;
 pub mod site_announcement;
 pub mod background_task;
+pub mod organization;
 pub mod token_route;
 pub mod user;

boosapi-rs/src/db/models/organization.rs

@@ -0,0 +1,39 @@
+use serde::{Deserialize, Serialize};
+use sqlx::FromRow;
+
+/// Organization for multi-tenant setup.
+#[derive(Debug, Clone, Serialize, Deserialize, FromRow)]
+pub struct Organization {
+    pub id: i64,
+    pub name: String,
+    pub slug: String,
+    pub plan: Option<String>,
+    pub status: Option<String>,
+    pub created_at: Option<String>,
+    pub updated_at: Option<String>,
+}
+
+/// Member of an organization.
+#[derive(Debug, Clone, Serialize, Deserialize, FromRow)]
+pub struct OrganizationMember {
+    pub id: i64,
+    pub org_id: i64,
+    pub user_id: i64,
+    pub role: Option<String>,
+    pub status: Option<String>,
+    pub joined_at: Option<String>,
+}
+
+/// Invitation to join an organization.
+#[derive(Debug, Clone, Serialize, Deserialize, FromRow)]
+pub struct Invitation {
+    pub id: i64,
+    pub org_id: i64,
+    pub email: String,
+    pub token: String,
+    pub role: Option<String>,
+    pub invited_by: Option<i64>,
+    pub status: Option<String>,
+    pub expires_at: Option<String>,
+    pub created_at: Option<String>,
+}