feat: add per-user tenant scoping

migrations/110_per_user_tenancy.sql

@@ -0,0 +1,22 @@
+-- Per-user tenancy: authenticate key/client id becomes an opaque tenant boundary.
+-- Existing rows remain in the legacy unscoped tenant (NULL) for single-tenant installs.
+
+alter table projects add column if not exists tenant_key text;
+alter table thoughts add column if not exists tenant_key text;
+alter table stored_files add column if not exists tenant_key text;
+alter table learnings add column if not exists tenant_key text;
+alter table plans add column if not exists tenant_key text;
+alter table chat_histories add column if not exists tenant_key text;
+
+-- Project names are now unique inside a tenant rather than globally.
+drop index if exists projects_name_key;
+create unique index if not exists projects_tenant_key_name_idx
+    on projects (coalesce(tenant_key, ''), name);
+
+create index if not exists projects_tenant_key_idx on projects (tenant_key);
+create index if not exists thoughts_tenant_key_idx on thoughts (tenant_key);
+create index if not exists thoughts_tenant_key_project_id_idx on thoughts (tenant_key, project_id);
+create index if not exists stored_files_tenant_key_idx on stored_files (tenant_key);
+create index if not exists learnings_tenant_key_idx on learnings (tenant_key);
+create index if not exists plans_tenant_key_idx on plans (tenant_key);
+create index if not exists chat_histories_tenant_key_idx on chat_histories (tenant_key);