Implicit then, between, starts/ends with — 339/831 (41%)

Biggest win: HS sources from upstream HTML had newlines replaced with
spaces, losing command separation. Now multi-space sequences become
'then' keywords, matching _hyperscript's implicit newline-as-separator
behavior. +42 tests passing.

Parser: 'is between X and Y', 'is not between', 'starts with',
'ends with' comparison operators.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/playwright/hs-behavioral.spec.js

@@ -323,9 +323,9 @@ test.describe('Hyperscript behavioral tests', () => {
       console.log(`    [${info.count}x] ${e}`);
     }
     // Show samples of "bar" error specifically
-    const barSamples = results.filter(r => !r.p && (r.e||'').includes('Assertion failed')).slice(0, 20);
+    const barSamples = results.filter(r => !r.p && (r.e||'').includes('Expected , got')).slice(0, 15);
     if (barSamples.length > 0) {
-      console.log(`  Assertion failures (${barSamples.length}):`);
+      console.log(`  Expected-got failures (${barSamples.length}):`);
       for (const s of barSamples) console.log(`    ${s.s}/${s.n}`);
     }