Add URL and SEO parity harnesses with fast-check fuzz testing

Generic URL parity harness (table-driven + property-based roundtrip)
and SEO parity harness (shape/completeness validation) registered for
Online Board. 170 tests covering all 6 route types with 200-iteration
fast-check fuzz runs ensuring no serialization asymmetry.

pnpm-lock.yaml

@@ -108,6 +108,9 @@ importers:
       eslint-plugin-unused-imports:
         specifier: ^4.0.0
         version: 4.4.1(@typescript-eslint/eslint-plugin@8.58.2(@typescript-eslint/parser@8.58.2(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3))(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3))(eslint@9.39.4(jiti@2.6.1))
+      fast-check:
+        specifier: ^4.6.0
+        version: 4.6.0
       jsdom:
         specifier: ^29.0.2
         version: 29.0.2
@@ -3863,6 +3866,10 @@ packages:
     resolution: {integrity: sha512-knvyeauYhqjOYvQ66MznSMs83wmHrCycNEN6Ao+2AeYEfxUIkuiVxdEa1qlGEPK+We3n0THiDciYSsCcgW/DoA==}
     engines: {node: '>=12.0.0'}
 
+  fast-check@4.6.0:
+    resolution: {integrity: sha512-h7H6Dm0Fy+H4ciQYFxFjXnXkzR2kr9Fb22c0UBpHnm59K2zpr2t13aPTHlltFiNT6zuxp6HMPAVVvgur4BLdpA==}
+    engines: {node: '>=12.17.0'}
+
   fast-deep-equal@3.1.3:
     resolution: {integrity: sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q==}
 
@@ -5308,6 +5315,9 @@ packages:
     resolution: {integrity: sha512-vYt7UD1U9Wg6138shLtLOvdAu+8DsC/ilFtEVHcH+wydcSpNE20AfSOduf6MkRFahL5FY7X1oU7nKVZFtfq8Fg==}
     engines: {node: '>=6'}
 
+  pure-rand@8.4.0:
+    resolution: {integrity: sha512-IoM8YF/jY0hiugFo/wOWqfmarlE6J0wc6fDK1PhftMk7MGhVZl88sZimmqBBFomLOCSmcCCpsfj7wXASCpvK9A==}
+
   qs@6.15.1:
     resolution: {integrity: sha512-6YHEFRL9mfgcAvql/XhwTvf5jKcOiiupt2FiJxHkiX1z4j7WL8J/jRHYLluORvc1XxB5rV20KoeK00gVJamspg==}
     engines: {node: '>=0.6'}
@@ -11060,6 +11070,10 @@ snapshots:
 
   expect-type@1.3.0: {}
 
+  fast-check@4.6.0:
+    dependencies:
+      pure-rand: 8.4.0
+
   fast-deep-equal@3.1.3: {}
 
   fast-glob@3.3.3:
@@ -12545,6 +12559,8 @@ snapshots:
 
   punycode@2.3.1: {}
 
+  pure-rand@8.4.0: {}
+
   qs@6.15.1:
     dependencies:
       side-channel: 1.1.0