feat(helpdesk): add software updates tracking with BC ticket integration

New Updates page in the Helpdesk module that fetches UPDATE/UPDATE-HF tickets
from Business Central (PBI_LV_Tickets) and allows assigning a domain and Gitea
link via a dialog. Ticket status (from BC) and assignment status (local) are
shown as separate columns with filters for both plus type and free-text search.
Assigned updates also appear on the domain detail page. Includes session-cached
BC fetch with refresh button, admin permissions, migration, and 16 unit tests.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

modules/helpdesk/migrations/008_create_updates.sql

@@ -0,0 +1,23 @@
+CREATE TABLE IF NOT EXISTS `helpdesk_updates` (
+    `id`            BIGINT UNSIGNED  NOT NULL AUTO_INCREMENT,
+    `tenant_id`     INT UNSIGNED     NOT NULL,
+    `ticket_no`     VARCHAR(30)      NOT NULL,
+    `category_code` VARCHAR(30)      NOT NULL,
+    `debitor_no`    VARCHAR(30)      NOT NULL,
+    `debitor_name`  VARCHAR(255)     NOT NULL DEFAULT '',
+    `domain_no`     VARCHAR(30)      NOT NULL DEFAULT '',
+    `domain_url`    VARCHAR(255)     NOT NULL DEFAULT '',
+    `gitea_path`    VARCHAR(255)     NOT NULL DEFAULT '',
+    `notes`         TEXT             NULL     DEFAULT NULL,
+    `status`        VARCHAR(20)      NOT NULL DEFAULT 'open',
+    `created_by`    INT UNSIGNED     NOT NULL,
+    `updated_by`    INT UNSIGNED     NULL     DEFAULT NULL,
+    `created_at`    DATETIME         NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    `updated_at`    DATETIME         NULL     DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP,
+    PRIMARY KEY (`id`),
+    UNIQUE KEY `uq_hu_ticket`  (`tenant_id`, `ticket_no`),
+    KEY `idx_hu_tenant`        (`tenant_id`),
+    KEY `idx_hu_domain`        (`tenant_id`, `domain_no`),
+    KEY `idx_hu_status`        (`tenant_id`, `status`),
+    KEY `idx_hu_debitor`       (`tenant_id`, `debitor_no`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;