feat(i18n): add multilingual OG tag support (closes #11)

- Add language column to #__mokoog_tags (default * for all languages)
- Updated unique key to include language
- SQL migration 01.02.00 for upgrades
- og:locale output from current Joomla language (en-GB to en_GB)
- Language-aware OG data loading: exact match preferred over wildcard

Authored-by: Moko Consulting

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

src/packages/com_mokoog/sql/install.mysql.sql

@@ -16,10 +16,11 @@ CREATE TABLE IF NOT EXISTS `#__mokoog_tags` (
     `meta_description` VARCHAR(200) NOT NULL DEFAULT '',
     `robots`         VARCHAR(100) NOT NULL DEFAULT '',
     `canonical_url`  VARCHAR(512) NOT NULL DEFAULT '',
+    `language`       CHAR(7) NOT NULL DEFAULT '*',
     `published`      TINYINT(1) NOT NULL DEFAULT 1,
     `created`        DATETIME NOT NULL DEFAULT '0000-00-00 00:00:00',
     `modified`       DATETIME NOT NULL DEFAULT '0000-00-00 00:00:00',
     PRIMARY KEY (`id`),
-    UNIQUE KEY `idx_content` (`content_type`, `content_id`),
+    UNIQUE KEY `idx_content_lang` (`content_type`, `content_id`, `language`),
     KEY `idx_published` (`published`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

src/packages/com_mokoog/sql/updates/mysql/01.02.00.sql

@@ -0,0 +1,10 @@
+--
+-- MokoOpenGraph 01.02.00 — Add multilingual OG tag support
+--
+
+ALTER TABLE `#__mokoog_tags`
+    ADD COLUMN `language` CHAR(7) NOT NULL DEFAULT '*' AFTER `canonical_url`;
+
+ALTER TABLE `#__mokoog_tags`
+    DROP INDEX `idx_content`,
+    ADD UNIQUE KEY `idx_content_lang` (`content_type`, `content_id`, `language`);