Add proof-measure client + bump to 1.4.0

proof-measure is a separate, public, unauthenticated Dragonchain service. Adds:
- UnauthHttpClient: HMAC-free transport mirroring DragonchainClient (timeout,
  agent, redirect refusal).
- ProofMeasureClient: getSecurity / report / health; default base URL
  https://proof-measure.dragonchain.com. Standalone (new ProofMeasureClient())
  and via DragonchainSDK.proofMeasure.
- Proof-measure types (decimals as strings, timestamps as numbers).
- jest tests.

README.md

@@ -145,6 +145,37 @@ await sdk.transactionType.delete('my-type');
 const block = await sdk.block.get('block-id');
 ```
 
+### Proof Measure (public, unauthenticated)
+
+`proof-measure` is a separate, **public, unauthenticated** Dragonchain service
+(the measured-immutability / "securedBy" metric) at
+`https://proof-measure.dragonchain.com`. It needs no credentials. Decimal fields
+are returned as strings (full precision) and timestamps as unix-second numbers.
+
+```typescript
+// Via the main SDK (targets the default public endpoint):
+const sec = await sdk.proofMeasure.getSecurity('BTC', Math.floor(Date.now() / 1000) - 3600);
+console.log(`BTC secured by ${sec.valueUsdFormatted} (${sec.raw.value} ${sec.raw.unit})`);
+
+// Or standalone — no prime credentials needed:
+import { ProofMeasureClient } from '@dragonchain-inc/prime-sdk';
+
+const pm = new ProofMeasureClient(); // or new ProofMeasureClient({ baseURL: '...' })
+
+const report = await pm.report({
+  transactionId: 'tx-123',
+  primeId: 'my-prime',
+  blockId: '42',
+  anchors: [
+    { network: 'BTC', txHash: '0x...', timestamp: anchorUnix },
+    { network: 'ETH', txHash: '0x...', timestamp: anchorUnix },
+  ],
+});
+console.log(`Secured by ${report.totalValueUsdFormatted} across ${report.anchors.length} anchors`);
+
+await pm.health();
+```
+
 ## TypeScript Support
 
 This SDK is written in TypeScript and includes complete type definitions: