feat: index parsed JSON fields of profile/channel/app-handler events

Kinds 0 (profile), 40/41 (channel create/metadata) and 31990 (app handler)
store their data as JSON in content. Implement SearchableEvent on them by
parsing the JSON (via the existing UserMetadata/ChannelData/AppMetadata
accessors) and indexing only the meaningful fields — names, bio/about, and
the addresses people search by: nip05 email, lightning addresses
(lud06/lud16), and website/picture/banner URLs. This avoids indexing the
JSON keys and structural punctuation that raw-content indexing would add.

Updates the FsSearchTest "non-searchable" case to use an unknown kind, since
MetadataEvent is now searchable, and adds SearchTest coverage for profile
and channel JSON fields (name, about, email, lightning, URL).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RFdWREvyvixRXnmNXNzmmN

quartz/src/jvmTest/kotlin/com/vitorpamplona/quartz/nip01Core/store/fs/FsSearchTest.kt

@@ -20,7 +20,7 @@
  */
 package com.vitorpamplona.quartz.nip01Core.store.fs
 
-import com.vitorpamplona.quartz.nip01Core.metadata.MetadataEvent
+import com.vitorpamplona.quartz.nip01Core.core.Event
 import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
 import com.vitorpamplona.quartz.nip01Core.signers.NostrSignerSync
 import com.vitorpamplona.quartz.nip10Notes.TextNoteEvent
@@ -117,17 +117,18 @@ class FsSearchTest {
     @Test
     fun `non-searchable event does not produce fts entries`() =
         runBlocking {
-            val meta =
-                signer.sign<MetadataEvent>(
+            // An event whose kind has no SearchableEvent mapping must not be indexed.
+            val nonSearchable =
+                signer.sign<Event>(
                     createdAt = 1,
-                    kind = MetadataEvent.KIND,
+                    kind = 9999,
                     tags = emptyArray(),
-                    content = "{\"name\":\"vitor\"}",
+                    content = "this text must not be indexed",
                 )
-            store.insert(meta)
+            store.insert(nonSearchable)
 
             val ftsRoot = root.resolve("idx/fts")
-            assertEquals(0, ftsRoot.listDirectoryEntries().size, "MetadataEvent is not SearchableEvent")
+            assertEquals(0, ftsRoot.listDirectoryEntries().size, "unknown kind is not SearchableEvent")
         }
 
     @Test