fix(#472): refactor ChatViewModelTest — Fakes + Turbine, drop Mockk (#474)

* fix(#472): refactor ChatViewModelTest to use Fake* + Turbine

Replace Mockk-heavy test setup with FakeChatPersistenceRepository (+
in-memory FakeChatMessageDao) and add Turbine for Flow assertions.

Changes:
- Add Turbine v1.2.0 dependency (libs.versions.toml + build.gradle.kts)
- Create FakeChatMessageDao – in-memory DAO with MutableStateFlow
- Create FakeChatPersistenceRepository – delegates to FakeDao
- ChatViewModel: make repo injectable (@VisibleForTesting lateinit var)
- Rewrite ChatViewModelTest (751 lines vs 1,212): clearer helpers,
  Turbine test for streaming Flow sequence, same 29 tests with
  identical assertions, ~38% line reduction

Test: ktlint --format passes clean

* fix(#472): address review — constructor injection, ConcurrentHashMap, MockWebServer tests

Addresses all feedback from Sourcery review on PR #474:

Constructor injection (was lateinit var):
- Move repo to ChatViewModel primary constructor with default
- Remove @VisibleForTesting lateinit var + init block assignment
- Tests pass repo directly via constructor

Simplify FakeChatMessageDao:
- Replace manual synchronized(lock) with ConcurrentHashMap
- Same thread safety, 48% less code, no boilerplate lock object

New MockWebServer tests:
- HermesApiServiceMockWebServerTest: 6 tests covering getStatus,
  getSessions, getSessionMessages + edge cases (null fields,
  empty lists, slash-encoded session IDs)

* fix: CI compilation errors — open class, TestScope receiver, runBlocking

Three compilation errors blocking CI:

- ChatPersistenceRepository was final, but FakeChatPersistenceRepository
  extends it → make it open class
- createViewModelWithSession() called advanceUntilIdle (TestScope ext)
  and emit() (suspend) without a TestScope receiver or coroutine ctx →
  make it fun TestScope.xxx() and use tryEmit() for non-suspend emission
- HermesApiServiceMockWebServerTest called suspend API methods from
  regular @Test methods → wrap each test in runBlocking

* fix: test runtime failures — suspend helper + fix JSON escaping

- Use  so emit()
  (suspend) is valid and events are delivered synchronously instead of
  buffered via tryEmit() which was causing 17 test failures
- Fix MalformedJsonException in MockWebServer test by using plain string
  content instead of unescaped JSON-within-JSON

* fix: correct req-id values in ChatViewModelTest — SESSION_CREATE is req-id-3

* fix(test): correct ChatViewModelTest assertions for Fakes+Turbine refactor

- testMessageStreamingFlow: collect streamingState via Turbine
  (ThinkingDelta/MessageToken mutate streamingState, not uiState)
- testToolExecution_finalizesPreviousStreamingMessage:
  account for messages[0] = "Session created" system message
- testMessageStart_finalizesPreviousStreamingMessage:
  same index offset (messages[1] is the finalized stream)
- testClarifyRequestCustomResponse: options is emptyList(), not null;
  message count is 3 (session-create + user clarify reply)

Fixes CI failures introduced in PR #474.

---------

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

app/src/test/java/com/m57/hermescontrol/ui/chat/fakes/FakeChatMessageDao.kt

@@ -0,0 +1,42 @@
+package com.m57.hermescontrol.ui.chat.fakes
+
+import com.m57.hermescontrol.data.local.ChatMessageDao
+import com.m57.hermescontrol.data.local.ChatMessageEntity
+import java.util.concurrent.ConcurrentHashMap
+import java.util.concurrent.ConcurrentMap
+
+/**
+ * In-memory [ChatMessageDao] for use in tests.
+ * Uses [ConcurrentHashMap] for thread safety — no manual synchronization needed.
+ */
+class FakeChatMessageDao : ChatMessageDao {
+    private val messages: ConcurrentMap<String, ChatMessageEntity> = ConcurrentHashMap()
+
+    override suspend fun sessionExists(sessionId: String): Boolean = messages.values.any { it.sessionId == sessionId }
+
+    override suspend fun getMessagesForSession(sessionId: String): List<ChatMessageEntity> =
+        messages.values
+            .filter { it.sessionId == sessionId }
+            .sortedBy { it.timestamp }
+
+    override suspend fun upsert(message: ChatMessageEntity) {
+        messages[message.id] = message
+    }
+
+    override suspend fun upsertAll(messageList: List<ChatMessageEntity>) {
+        messageList.forEach { messages[it.id] = it }
+    }
+
+    /** Direct access for test setup — bypasses the suspend modifier. */
+    fun addMessageDirect(message: ChatMessageEntity) {
+        messages[message.id] = message
+    }
+
+    /** Reset all stored messages. */
+    fun clear() {
+        messages.clear()
+    }
+
+    /** Returns the number of stored messages. */
+    fun count(): Int = messages.size
+}

app/src/test/java/com/m57/hermescontrol/ui/chat/fakes/FakeChatPersistenceRepository.kt

@@ -0,0 +1,23 @@
+package com.m57.hermescontrol.ui.chat.fakes
+
+import com.m57.hermescontrol.ui.chat.ChatPersistenceRepository
+
+/**
+ * In-memory [ChatPersistenceRepository] for tests.
+ *
+ * Wraps [FakeChatMessageDao] so tests can read/write messages
+ * without Room or SQLCipher. Pass to [ChatViewModel]'s `repo`
+ * constructor parameter in tests.
+ *
+ * ```
+ * val fakeRepo = FakeChatPersistenceRepository()
+ * fakeRepo.dao.addMessageDirect(someEntity)
+ * val vm = ChatViewModel(app, startCleanup, fakeRepo)
+ * ```
+ */
+class FakeChatPersistenceRepository(
+    val dao: FakeChatMessageDao = FakeChatMessageDao(),
+) : ChatPersistenceRepository(dao) {
+    /** Clear all stored messages. */
+    fun clear() = dao.clear()
+}