Refactor: Modernize for Java 25 & Fix Velocity Proxy Deadlocks (v2.1.3)

📝 Description

This PR focuses on updating the core infrastructure to align with the bleeding-edge Minecraft 26.1.2 / Java 25 ecosystem. It also contains a critical fix for a cross-server data deadlock issue that occurred when switching servers on our proxy network.

🐛 Bug Fixes

• Velocity Server Switch Deadlocks: Resolved a critical cross-server data lock issue where the proxy failed to gracefully intercept server transfers and release player SQL locks prior to routing.
• Annotation Processor Mitigation: The root cause of the proxy deadlock was traced back to our Java 25 / Maven Annotation Processors suppressing proxy integration endpoints during compilation. By explicitly passing the @Plugin Velocity API annotation directly into the compiler arguments array, we've successfully recovered the generation of the velocity-plugin.json initialization file. The proxy component now initializes and intercepts transfers cleanly.
• Structural Null Safety: Resolved BungeeCord and Velocity ByteArrayDataOutput.writeUTF structural inference problems around UUID String boundaries to ensure strict conformance to Guava expectations.

🚀 Modernization & Technical Debt

• API Standardization:
  • Updated paper-api to 26.1.2.build.7-alpha.
  • Updated velocity-api to 3.5.0-SNAPSHOT (Build #592).
  • Updated item-nbt-api to 2.15.7.
  • Updated testing dependencies (mockito) to 5.23.0.
• Legacy Refactors:
  • Migrated health sync properties to utilize Attribute.MAX_HEALTH, fully deprecating the legacy GENERIC_ prefix requirements targeting modern APIs.
  • Restructured PlayerQuitEvent logic in our flow suites to adopt modern Component adventure text system, erasing legacy string deprecations natively.
  • Upgraded internal plugin message events to correctly route their legacy event parameters, accommodating proxy-transfer flags natively.

🛡 Zero-Suppression Defensive Null Safety

• Phased out @SuppressWarnings for null validation loops across the entire bridge logic constraint map, replacing them with mechanically enforced java.util.Objects.requireNonNull validation layers cleanly.
• Safely rewired ambiguous core Bukkit states (getLocation, advancementIterator, getCommand) to aggressively trap and seal implicit analyzer NPE leakages directly inside the event pipeline.

🏗 Build Pipeline Adjustments

• Upgraded compiler compliance matrix to strictly target Java 25 (<release>25</release>).
• Bumped maven-shade-plugin natively to 3.6.2, and injected cutting-edge org.ow2.asm 9.9.1 dependencies to successfully resolve shade failures against Java 25's new major bytecode signatures.

🧪 Testing & Verification

• Verified compilation integrity on Java 25.
• Live tested on proxy environment (Velocity 3.5.0 handling two PaperMC 26.1.2 instances).
• Tested rapid server hopping back-and-forth between instances.
• Verified perfect synchronization across Health, Inventory, and complex NBT data during immediate server switches with zero proxy timeouts or deadlocks.