API-style comments and ktlint formatting

Every comment is reduced to its first sentence plus @param, @return
and @throws tags. Comment lines: 20040 to 8526. ktlint 1.8 applied
with its default (official Kotlin) style across all modules; 262 files
reformatted. The 264 remaining ktlint findings are naming and filename
rules, which are code changes, and are left alone.

Comments and formatting only. 1208 tests pass, counted from the XML.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

engine/src/test/kotlin/io/flamenet/e2e/DisappearingTest.kt

@@ -1,34 +1,40 @@
 package io.flamenet.e2e
 
-import javax.crypto.KeyGenerator
 import org.json.JSONObject
+import javax.crypto.KeyGenerator
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertTrue
 
 /**
  * Disappearing messages (§6.11), at the vault.
- *
- * Expiry runs on read. A sweep on a timer leaves
- * expired messages on disk between runs, and a "disappearing" message still
- * sitting in the vault is a claim rather than a feature. Reading is the one
- * path every caller shares.
  */
 class DisappearingTest {
-
     private class MapStorage : Vault.Storage {
         private val records = mutableMapOf<String, ByteArray>()
+
         override fun read(name: String) = records[name]
-        override fun write(name: String, bytes: ByteArray) { records[name] = bytes }
-        override fun delete(name: String) { records.remove(name) }
+
+        override fun write(
+            name: String,
+            bytes: ByteArray,
+        ) {
+            records[name] = bytes
+        }
+
+        override fun delete(name: String) {
+            records.remove(name)
+        }
+
         override fun names() = records.keys.toList()
     }
 
-    private fun vault() = Vault(
-        MapStorage(), KeyGenerator.getInstance("AES").apply { init(256) }.generateKey())
+    private fun vault() = Vault(MapStorage(), KeyGenerator.getInstance("AES").apply { init(256) }.generateKey())
 
-    private fun line(text: String, at: Long) =
-        JSONObject().put("text", text).put("mine", true).put("at", at)
+    private fun line(
+        text: String,
+        at: Long,
+    ) = JSONObject().put("text", text).put("mine", true).put("at", at)
 
     private val now = 1_700_000_000_000L
 
@@ -66,9 +72,7 @@ class DisappearingTest {
     }
 
     /**
-     * A message with no timestamp predates the field. An unknown age is not
-     * evidence of an old one, and deleting somebody's history on a guess cannot
-     * be undone.
+     * A message with no timestamp predates the field.
      */
     @Test
     fun `a message with no timestamp is kept`() {