feat(core): DHCP client after Java, measured with Java FILIUS

The client follows Java's DHCPClient instead of Swift: one DISCOVER or
REQUEST per attempt, an answer that does not fit is read and dropped, the
ARP check waits a round trip (an answer for the address ends it at once,
then DECLINE), a timeout repeats the state's message, and the fifth turns
to a link-local address 169.254.1.x/16 (ARP probe, ARP reply to all); no
old address is given back. DHCP round trip times follow the speed as in
Java (50 cables, 2750 ms at 90 %; Swift: fixed 2500 ms).

Not taken from Java: the client gives up after five occupied link-local
addresses (Java searches on without end), and an ARP packet for another
address does not end the check.

dhcpJava.test.ts compares the four DHCP scenarios with DhcpRun's Java
runs; the Swift comparison only checks that they differ.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/core/src/runtime/random.ts

@@ -50,6 +50,11 @@ export class JavaCompatibleRandom {
     return Math.fround(this.next(24) / (1 << 24));
   }
 
+  /** Java's nextDouble (what Math.random draws): 53 random bits over 2^53. */
+  nextDouble(): number {
+    return (this.next(26) * 2 ** 27 + this.next(27)) / 2 ** 53;
+  }
+
   /** Java RIP: 30 s · (f/3 + 0.84), truncated — somewhere between 25.2 s and 35.2 s. */
   nextRipJitterMilliseconds(): number {
     const javaFloat = this.nextFloat();