fix: emit repeated keyterm query params for multi-keyterm streaming

[jkroll-deepgram]

Summary

The listen v1 (Nova-3) and v2 (Flux) streaming WebSocket clients mis-serialize a multi-value keyterm. When keyterm is a List<String>, the client stringifies the whole list into a single query param instead of emitting repeated params:

❌ keyterm=%5Ba%2C+b%5D        // one param, value "[a, b]"
✅ keyterm=a&keyterm=b          // one param per term (correct)

Per the keyterm docs, multiple key terms must be sent as repeated keyterm= params. The server treats the stringified list as a single nonsense term, so instead of boosting the intended terms, it degrades recognition of them.

Root cause

Both streaming clients build the query with:

urlBuilder.addQueryParameter("keyterm", String.valueOf(options.getKeyterm().get()));

String.valueOf(...) on a List<String> yields Java's list toString() — [a, b] — which okhttp then percent-encodes into one param. The prerecorded/REST path is unaffected (it uses QueryStringMapper with arraysAsRepeats).

Fix

Emit one keyterm param per term in both streaming clients (instanceof Iterable handles the List case; scalar string keyterms are unchanged). Also freeze V1WebSocketClient.java in .fernignore — V2WebSocketClient.java was already frozen, so otherwise the v1 fix would be lost on the next Fern regeneration.

Impact

• Single-string keyterms: unchanged.
• Multi-keyterm streaming: now correct. Before this fix there was no way to send more than one keyterm on a streaming connection — of(List.of(...)) mangled the value, and even a one-element list produced [term].

Tests

Added connect-handshake wire coverage (MockWebServer, asserting the captured upgrade URL):

• ListenV2ConnectWireTest (Flux): list → repeated params; single string → one param.
• ListenV1ConnectWireTest (Nova-3, new): list → repeated params.

Existing numerals wire tests still pass. ./gradlew spotlessJavaCheck test is green.

Manual verification

Streamed a real audio clip to Flux (flux-general-en) with a two-element keyterm list, real-time paced:

keyterm	before	after
List.of("a", "b")	boosted term consistently mis-transcribed (6/6)	correct (5/5)
"a" (single)	correct	correct
none	correct	correct