Packaged Core 1.0.62 - Ethium Buckler

Item: joergry_compat:ethium_buckler
Smithing: Ethium upgrade tablet + Modular Backpacks Netherite Buckler + Ethium ingot.
Uses the same smithing_transform recipe type as Ethium equipment, preserving base-item component patches through vanilla smithing behavior.

Per installed Ethium module: +4 armor, +1 armor toughness, +10% knockback resistance.
When at least one Ethium module is present: all buckler armor caps at 7 and combined buckler knockback resistance caps at 15%.
Existing native toughness cap is preserved: 3 with Netherite/Ethium, 2 otherwise.
Examples: Ethium alone = 4 armor / 1 toughness / 10% resistance; Ethium + Netherite = 7 / 2.5 / 15%; two Ethium = 7 / 2 / 15%; four Ethium = 7 / 3 / 15%.

Extends the native BucklerItem with the Netherite flags and geometry, preserving normal module insertion, damage wear, fire-wear immunity and dropped-backpack fire protection. Durability 495 follows the native helmet-durability convention (Ethium 11*45, compared to Netherite 11*37=407). Anvil repair ingredient is Ethium ingot. Native Shift-tooltip styling and Modular Backpacks creative tab.
Uses the supplied ethium_buckler.png item icon and buckler4.png model texture unchanged. Texture selection is per module slot, allowing mixed Netherite and Ethium appearances. Native backpack armor panel is extended to display up to 7 points using its normal armor sprites.
Only the native buckler attribute modifiers are replaced, inside the native refresh hook and only when Ethium is present. No independent tick handler; no bonus from ordinary storage. No armor/toughness/knockback changes without an Ethium module.

Validation: compiled against installed Modular Backpacks API; native BucklerItem flags/methods tested; exhaustive 625 four-slot combinations; mixed caps; repeat refresh; live/saved handlers; texture-slot mapping; exact injection descriptors and annotation retention; JSON/ZIP integrity and unchanged-existing-entry verification. Runtime test fixtures are isolated and not shipped. Full Minecraft launch and in-game visual testing unavailable.

Suggested future additions, not included: an Aether altar repair recipe and a Create crushing recipe following the other buckler modules.
