Expand material support and checkpoint the completed building toolkit

Expose the runtime block/item registry through compact material search and
single-material descriptions. Preserve private block-entity data through
checked edits and durable undo without sending payloads to model context.

Include the completed terrain tools, isolated world/map plugin, station lift,
ACP streaming and guidance fixes, local camera auto-connect, construction
scripts, and their public documentation, references and verification records.
Active station decoration and private runtime data remain outside this commit.

Validation: 145 Maven tests, 47 Bridge tests, successful camera Gradle build,
and isolated Paper verification of all 1,196 block defaults plus 5,392
independent property cases for placement, same-material edits and restoration.

pom.xml

@@ -1,7 +1,7 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <groupId>io.github.minecraftbuilder</groupId><artifactId>minecraft-builder-mcp</artifactId><version>0.1.0-SNAPSHOT</version><packaging>pom</packaging>
-  <modules><module>world-core</module><module>paper-plugin</module></modules>
+  <modules><module>world-core</module><module>paper-plugin</module><module>terrain-world-plugin</module></modules>
   <properties><maven.compiler.release>25</maven.compiler.release><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><paper.version>26.2.build.123-stable</paper.version></properties>
   <build><pluginManagement><plugins>
     <plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>3.14.1</version></plugin>