Release version 1.2.8 - Currency display and data deletion fixes

Fixed two important bugs reported in v1.2.7:

Bug 1: Currency Symbol Missing in Admin Headers and Placeholders
- Table headers now show "Price (CURRENCY)" instead of just "Price"
- Input placeholders include currency symbol (e.g., "9.99 $")
- Better UX for multi-currency stores

Bug 2: Variation Pricing Data Not Deleted Properly (Critical)
- Empty pricing arrays were being saved instead of deleted
- Fixed save logic to check if arrays are empty after filtering
- Properly deletes post meta when all entries are removed
- Affects simple products, variable parents, and variations

Technical changes:
- Updated all table headers with currency symbol display
- Modified all render methods to pass currency_symbol to templates
- Updated Twig templates to use currency in placeholders
- Fixed save_tier_package_fields() and save_variation_pricing_fields()
- Added !empty() checks before update_post_meta() calls

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

templates/admin/tier-row.twig

@@ -21,7 +21,7 @@
         <input type="text"
                name="{{ name_prefix }}[{{ index|esc_attr }}][price]"
                value="{{ tier.price|default('')|esc_attr }}"
-               placeholder="{{ 'e.g., 9.99'|__('wc-tier-package-prices') }}"
+               placeholder="{{ ('e.g., 9.99 ' ~ currency_symbol)|__('wc-tier-package-prices') }}"
                class="short wc_input_price">
     </td>
     <td>