feat(nests): emit catalog jitter hint matching Opus frame duration

hang.js's encoder publishes a `jitter` field (ms) in every audio
rendition; the watcher uses it to size its jitter buffer. Without it
the watcher falls back to a built-in default — works in practice today
but means our publishes deviate from the canonical hang shape and the
deviation could surface as audible buffer-sizing differences on a
future watcher revision that takes the field as required.

Add `jitter: 20` to MoqLiteHangCatalog.AudioRendition (matching the
Opus frame cadence: 960 samples at 48 kHz = 20 ms; same value hang.js
hard-codes at `js/publish/src/audio/encoder.ts:#runConfig`). Updates
the byte-exact MoqLiteHangCatalogTest assertion and the parallel
inline-literal in RoomSpeakerCatalogTest so both sides stay pinned.

The commons-side `RoomSpeakerCatalog` parser doesn't surface the new
field — `JsonMapper`'s `ignoreUnknownKeys = true` lets the watcher
ingest it silently. Adding a typed `jitter` field there is a
forward-compat task; not needed for interop with hang today.

https://claude.ai/code/session_014JfZJHSTvyYYWJbC9VbB47

nestsClient/src/commonTest/kotlin/com/vitorpamplona/nestsclient/moq/lite/MoqLiteHangCatalogTest.kt

@@ -33,7 +33,7 @@ class MoqLiteHangCatalogTest {
         val expected =
             "{\"audio\":{\"renditions\":{\"audio/data\":{" +
                 "\"codec\":\"opus\",\"container\":{\"kind\":\"legacy\"}," +
-                "\"sampleRate\":48000,\"numberOfChannels\":1}}}}"
+                "\"sampleRate\":48000,\"numberOfChannels\":1,\"jitter\":20}}}}"
         val actual =
             MoqLiteHangCatalog.opusMono48k("audio/data").encodeJsonBytes().decodeToString()
         assertEquals(expected, actual)