Add /kamkeel testfont GUI and scalable OpenSans renderer

[KAMKEEL]

Motivation

• Provide an in-game example GUI that demonstrates crisp, scalable text rendering using the existing TTF shipped in resources.
• Offer a client-only debug/demo screen that proves alignment (baseline/grid), renderer details and works via the existing KAMKEEL command system.
• Ship a robust renderer that prefers SDF+shader for sharp scaling and falls back to per-size rebaked atlases to avoid blurry bitmap scaling.

Description

• Added a client-side GUI GuiFontTest that hardcodes the discovered font path assets/customnpcs/OpenSans.ttf and draws a title, sample text at sizes 8, 12, 16, 24, 32, 48, 64, baseline markers, and debug info. (new file: src/main/java/noppes/npcs/client/gui/GuiFontTest.java)
• Implemented ScalableFontRenderer which loads the TTF from the classpath, builds an SDF atlas and renders via a GLSL (GL20) shader, with a deterministic per-size raster rebake fallback if shaders fail; atlas upload uses GL_LINEAR filtering and GL_CLAMP_TO_EDGE, glyphs rendered as quads batched with Tessellator, and GL state is pushed/popped to avoid affecting vanilla GUI state. (new file: src/main/java/noppes/npcs/client/gui/font/ScalableFontRenderer.java)
• Added a server-to-client packet GuiFontTestPacket and a server-side TestCommand mapped into the existing KAMKEEL command set so /kamkeel testfont opens the GUI client-side; packet and command are client-safe. (new files: src/main/java/kamkeel/npcs/network/packets/data/gui/GuiFontTestPacket.java, src/main/java/kamkeel/npcs/command/TestCommand.java)
• Registered the new packet and command: updated CommandKamkeel to register the command, added GUI_FONT_TEST to EnumDataPacket, and registered the packet in PacketHandler. (modified files: src/main/java/kamkeel/npcs/command/CommandKamkeel.java, src/main/java/kamkeel/npcs/network/enums/EnumDataPacket.java, src/main/java/kamkeel/npcs/network/PacketHandler.java)

Testing

• Ran the repository initialization steps: git submodule sync --recursive and git submodule update --init --recursive to ensure API and gradle-plugin submodules were present; these completed successfully.
• Executed the compile check ./gradlew compileJava; an environment toolchain issue was addressed during CI setup and the final build completed successfully with BUILD SUCCESSFUL.
• Automated build output summary: BUILD SUCCESSFUL in 2m 3s (compile task completed without errors).

---

Codex Task