refactor(license): extract cameleer-license-api module from server-core

Splits the pure license contract types (LicenseInfo, LicenseValidator,
LicenseState, LicenseStateMachine, LicenseLimits, DefaultTierLimits) into a
new cameleer-license-api module under package com.cameleer.license.

Why: cameleer-license-minter previously depended on cameleer-server-core for
these types, dragging cameleer-server-core + cameleer-common onto the
classpath of every minter consumer (notably cameleer-saas). The SaaS
management plane has no business carrying server-runtime types — it only
needs the license contract to mint and verify tokens.

After:
  cameleer-license-minter -> cameleer-license-api  (no server internals)
  cameleer-server-core    -> cameleer-license-api
  cameleer-saas           -> cameleer-license-minter -> cameleer-license-api

Verified: mvn -pl cameleer-license-minter dependency:tree shows the minter
no longer pulls cameleer-server-core or cameleer-common. Full reactor
verify (-DskipITs) green: 371 tests pass.

LicenseGate stays in server-core (server-runtime state holder, not contract).

Closes cameleer/cameleer-server#156

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cameleer-license-api/pom.xml

@@ -0,0 +1,54 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>com.cameleer</groupId>
+        <artifactId>cameleer-server-parent</artifactId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>cameleer-license-api</artifactId>
+    <name>Cameleer License API</name>
+    <description>Pure license contract types — LicenseInfo, LicenseValidator, LicenseState, LicenseStateMachine, LicenseLimits, DefaultTierLimits. Shared by server-core (validation/runtime gate) and cameleer-license-minter (vendor-side signing). Has no Spring or server-runtime dependencies so consumers like cameleer-saas can depend on the minter without inheriting server internals.</description>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+                <executions>
+                    <!-- Plain library JAR — no repackage. -->
+                    <execution>
+                        <id>repackage</id>
+                        <phase>none</phase>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>