Add migration for old sqlite timestamps (#869)

* add migration for old sqlite timestamps

* format python file + add support for negative timezones

backend/internal/data/migrations/sqlite3/20250706190000_generate_migration.py

@@ -0,0 +1,61 @@
+#!/usr/bin/env python
+import os
+
+# Extract fields with
+""" WITH tables AS (
+  SELECT name AS table_name
+  FROM sqlite_master
+  WHERE type = 'table'
+    AND name NOT LIKE 'sqlite_%'
+)
+
+SELECT
+  '["' || t.table_name || '", "' || c.name || '"],' AS table_column
+FROM tables t
+JOIN pragma_table_info(t.table_name) c
+WHERE c.name like'%date%'; """
+
+fields = [["auth_tokens", "created_at"],
+          ["auth_tokens", "updated_at"],
+          ["auth_tokens", "expires_at"],
+          ["groups", "created_at"],
+          ["groups", "updated_at"],
+          ["group_invitation_tokens", "created_at"],
+          ["group_invitation_tokens", "updated_at"],
+          ["group_invitation_tokens", "expires_at"],
+          ["item_fields", "created_at"],
+          ["item_fields", "updated_at"],
+          ["item_fields", "time_value"],
+          ["labels", "created_at"],
+          ["labels", "updated_at"],
+          ["locations", "created_at"],
+          ["locations", "updated_at"],
+          ["maintenance_entries", "created_at"],
+          ["maintenance_entries", "updated_at"],
+          ["maintenance_entries", "date"],
+          ["maintenance_entries", "scheduled_date"],
+          ["notifiers", "created_at"],
+          ["notifiers", "updated_at"],
+          ["users", "created_at"],
+          ["users", "updated_at"],
+          ["users", "activated_on"],
+          ["items", "created_at"],
+          ["items", "updated_at"],
+          ["items", "warranty_expires"],
+          ["items", "purchase_time"],
+          ["items", "sold_time"],
+          ["attachments", "created_at"],
+          ["attachments", "updated_at"]]
+
+
+def generate_migration(table_name, field_name):
+    return f"""update {table_name} set {field_name} = substr({field_name},1, instr({field_name}, ' +')-1) || substr({field_name}, instr({field_name}, ' +')+1,3) || ':' || substr({field_name}, instr({field_name}, ' +')+4,2) where {field_name} like '% +%';\n""" + \
+           f"""update {table_name} set {field_name} = substr({field_name},1, instr({field_name}, ' -')-1) || substr({field_name}, instr({field_name}, ' -')+1,3) || ':' || substr({field_name}, instr({field_name}, ' -')+4,2) where {field_name} like '% -%';"""
+
+
+print("-- +goose Up")
+print(f"-- GENERATED with {os.path.basename(__file__)}")
+for table, column in fields:
+    print(f"-- Migrating {table}/{column}")
+    print(generate_migration(table, column))
+    print()