core, ui: chat relay test (#6736)

src/Simplex/Chat/Store/SQLite/Migrations/M20260222_chat_relays.hs

@@ -80,6 +80,8 @@ ALTER TABLE messages ADD COLUMN msg_chat_binding TEXT;
 ALTER TABLE messages ADD COLUMN msg_signatures BLOB;
 
 ALTER TABLE chat_items ADD COLUMN msg_signed TEXT;
+
+ALTER TABLE connections ADD COLUMN relay_test INTEGER NOT NULL DEFAULT 0;
 |]
 
 down_m20260222_chat_relays :: Query
@@ -124,4 +126,6 @@ ALTER TABLE messages DROP COLUMN msg_chat_binding;
 ALTER TABLE messages DROP COLUMN msg_signatures;
 
 ALTER TABLE chat_items DROP COLUMN msg_signed;
+
+ALTER TABLE connections DROP COLUMN relay_test;
 |]

src/Simplex/Chat/Store/SQLite/Migrations/chat_query_plans.txt

@@ -1764,6 +1764,15 @@ Query:
 Plan:
 SEARCH groups USING INTEGER PRIMARY KEY (rowid=?)
 
+Query: 
+        INSERT INTO connections (
+          user_id, agent_conn_id, conn_level, conn_status, conn_type,
+          conn_chat_version, to_subscribe, pq_support, pq_encryption,
+          relay_test, created_at, updated_at
+        ) VALUES (?,?,?,?,?,?,?,?,?,?,?,?)
+      
+Plan:
+
 Query: 
         INSERT INTO connections (
           user_id, agent_conn_id, conn_level, conn_status, conn_type,
@@ -3293,6 +3302,13 @@ Query:
 Plan:
 SEARCH connections USING INDEX idx_connections_contact_id (contact_id=?)
 
+Query: 
+        SELECT agent_conn_id FROM connections
+        WHERE user_id = ? AND relay_test = 1 AND created_at < ?
+      
+Plan:
+SEARCH connections USING INDEX idx_connections_to_subscribe (user_id=?)
+
 Query: 
         SELECT c.agent_conn_id
         FROM connections c

src/Simplex/Chat/Store/SQLite/Migrations/chat_schema.sql

@@ -340,6 +340,7 @@ CREATE TABLE connections(
   short_link_inv BLOB,
   via_short_link_contact BLOB,
   via_contact_uri BLOB,
+  relay_test INTEGER NOT NULL DEFAULT 0,
   FOREIGN KEY(snd_file_id, connection_id)
   REFERENCES snd_files(file_id, connection_id)
   ON DELETE CASCADE