fix: Reject zero values in ResourceQuota.Builder (#168)

Changed validation to require positive values (> 0) instead of non-negative
(>= 0) for resource limits, preventing impossible-to-satisfy quotas.

Changes:
- maxHeapBytes() now requires bytes > 0
- maxThreadCount() now requires count > 0
- maxCpuTimeNanos() now requires nanos > 0
- Updated all error messages from ">= 0" to "> 0"
- Updated tests to verify zero values are rejected
- Total 13 tests passing

This ensures:
- Resource quotas represent realistic, enforceable limits
- Any application can potentially satisfy the quota
- Clear error messages at build time for impossible quotas

Fixes #168: ResourceQuota.Builder allows 0 for resource limits - creates
impossible quotas

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: Flossy

jplatform-api/src/main/java/org/flossware/jplatform/api/ResourceQuota.java

@@ -120,13 +120,13 @@ public static class Builder {
         /**
          * Sets the maximum heap memory allowed.
          *
-         * @param bytes the maximum heap size in bytes
+         * @param bytes the maximum heap size in bytes (must be positive)
          * @return this builder
-         * @throws IllegalArgumentException if bytes is negative
+         * @throws IllegalArgumentException if bytes is zero or negative
          */
         public Builder maxHeapBytes(long bytes) {
-            if (bytes < 0) {
-                throw new IllegalArgumentException("maxHeapBytes must be >= 0, got: " + bytes);
+            if (bytes <= 0) {
+                throw new IllegalArgumentException("maxHeapBytes must be > 0, got: " + bytes);
             }
             this.maxHeapBytes = Optional.of(bytes);
             return this;
@@ -135,13 +135,13 @@ public Builder maxHeapBytes(long bytes) {
         /**
          * Sets the maximum number of threads allowed.
          *
-         * @param count the maximum thread count
+         * @param count the maximum thread count (must be positive)
          * @return this builder
-         * @throws IllegalArgumentException if count is negative
+         * @throws IllegalArgumentException if count is zero or negative
          */
         public Builder maxThreadCount(int count) {
-            if (count < 0) {
-                throw new IllegalArgumentException("maxThreadCount must be >= 0, got: " + count);
+            if (count <= 0) {
+                throw new IllegalArgumentException("maxThreadCount must be > 0, got: " + count);
             }
             this.maxThreadCount = Optional.of(count);
             return this;
@@ -150,13 +150,13 @@ public Builder maxThreadCount(int count) {
         /**
          * Sets the maximum CPU time allowed.
          *
-         * @param nanos the maximum CPU time in nanoseconds
+         * @param nanos the maximum CPU time in nanoseconds (must be positive)
          * @return this builder
-         * @throws IllegalArgumentException if nanos is negative
+         * @throws IllegalArgumentException if nanos is zero or negative
          */
         public Builder maxCpuTimeNanos(long nanos) {
-            if (nanos < 0) {
-                throw new IllegalArgumentException("maxCpuTimeNanos must be >= 0, got: " + nanos);
+            if (nanos <= 0) {
+                throw new IllegalArgumentException("maxCpuTimeNanos must be > 0, got: " + nanos);
             }
             this.maxCpuTimeNanos = Optional.of(nanos);
             return this;

jplatform-api/src/test/java/org/flossware/jplatform/api/ResourceQuotaTest.java

@@ -29,16 +29,30 @@ void testBuilderAcceptsValidValues() {
     }
 
     @Test
-    void testBuilderAcceptsZeroValues() {
-        ResourceQuota quota = ResourceQuota.builder()
-                .maxHeapBytes(0)
-                .maxThreadCount(0)
-                .maxCpuTimeNanos(0)
-                .build();
+    void testBuilderRejectsZeroHeapBytes() {
+        IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> {
+            ResourceQuota.builder().maxHeapBytes(0);
+        });
+
+        assertTrue(exception.getMessage().contains("maxHeapBytes must be > 0"));
+    }
+
+    @Test
+    void testBuilderRejectsZeroThreadCount() {
+        IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> {
+            ResourceQuota.builder().maxThreadCount(0);
+        });
+
+        assertTrue(exception.getMessage().contains("maxThreadCount must be > 0"));
+    }
+
+    @Test
+    void testBuilderRejectsZeroCpuTimeNanos() {
+        IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> {
+            ResourceQuota.builder().maxCpuTimeNanos(0);
+        });
 
-        assertEquals(0L, quota.getMaxHeapBytes().get());
-        assertEquals(0, quota.getMaxThreadCount().get());
-        assertEquals(0L, quota.getMaxCpuTimeNanos().get());
+        assertTrue(exception.getMessage().contains("maxCpuTimeNanos must be > 0"));
     }
 
     @Test
@@ -47,7 +61,7 @@ void testBuilderRejectsNegativeHeapBytes() {
             ResourceQuota.builder().maxHeapBytes(-512);
         });
 
-        assertEquals("maxHeapBytes must be >= 0, got: -512", exception.getMessage());
+        assertEquals("maxHeapBytes must be > 0, got: -512", exception.getMessage());
     }
 
     @Test
@@ -56,7 +70,7 @@ void testBuilderRejectsNegativeThreadCount() {
             ResourceQuota.builder().maxThreadCount(-10);
         });
 
-        assertEquals("maxThreadCount must be >= 0, got: -10", exception.getMessage());
+        assertEquals("maxThreadCount must be > 0, got: -10", exception.getMessage());
     }
 
     @Test
@@ -65,7 +79,7 @@ void testBuilderRejectsNegativeCpuTimeNanos() {
             ResourceQuota.builder().maxCpuTimeNanos(-1000);
         });
 
-        assertEquals("maxCpuTimeNanos must be >= 0, got: -1000", exception.getMessage());
+        assertEquals("maxCpuTimeNanos must be > 0, got: -1000", exception.getMessage());
     }
 
     @Test