Composer auto-grow (1→5 lines) + in-field attach; settings screen + persisted prefs

- Composer input starts at one line and auto-grows up to 5 lines (then scrolls),
  measured via onTextLayout; attach (paperclip) moved inside the field, right of
  the text, per the Telegram reference.

- New SettingsScreen (drawer/rail entry) for Threads + Tool detail; both now
  persist via SecureStore (Android prefs / desktop JSON).

- Add AGENTS.md; rename reference screenshot to telegram_screenshot_reference.jpg.

app/shared/src/commonMain/kotlin/iris/state/IrisController.kt

@@ -80,8 +80,9 @@ class IrisController(
     private val _typing = MutableStateFlow(false)
     val typing: StateFlow<Boolean> = _typing.asStateFlow()
 
-    /** Tool-card verbosity (M2). NOTHING suppresses tool cards entirely. */
-    private val _toolDetail = MutableStateFlow(ToolDetail.TRUNCATED)
+    /** Tool-card verbosity (M2). NOTHING suppresses tool cards entirely.
+     *  Persisted (Settings → "Tool detail"). */
+    private val _toolDetail = MutableStateFlow(ToolDetail.fromName(store.toolDetail))
     val toolDetail: StateFlow<ToolDetail> = _toolDetail.asStateFlow()
 
     fun cycleToolDetail() {
@@ -90,6 +91,13 @@ class IrisController(
             ToolDetail.TRUNCATED -> ToolDetail.NOTHING
             ToolDetail.NOTHING -> ToolDetail.EVERYTHING
         }
+        store.toolDetail = _toolDetail.value.name.lowercase()
+    }
+
+    fun setToolDetail(detail: ToolDetail) {
+        if (detail == _toolDetail.value) return
+        _toolDetail.value = detail
+        store.toolDetail = detail.name.lowercase()
     }
 
     /** Home channel id (from hello.ack; default until then). */
@@ -101,11 +109,13 @@ class IrisController(
     val gatewayStatus: StateFlow<String?> = _gatewayStatus.asStateFlow()
 
     // ── M3: threads toggle (per-app for now; per-channel lands later) ─────
-    private val _threadsEnabled = MutableStateFlow(false)
+    // Persisted (Settings → "Threads").
+    private val _threadsEnabled = MutableStateFlow(store.threadsEnabled)
     val threadsEnabled: StateFlow<Boolean> = _threadsEnabled.asStateFlow()
 
     fun toggleThreads() {
         _threadsEnabled.value = !_threadsEnabled.value
+        store.threadsEnabled = _threadsEnabled.value
     }
 
     // ── M3: search state ──────────────────────────────────────────────────
@@ -487,4 +497,11 @@ enum class ToolDetail {
     EVERYTHING,   // name + full args (collapsible) + output preview
     TRUNCATED,    // one-liner "emoji name: preview", collapsible (default)
     NOTHING,      // suppress tool cards entirely
+    ;
+
+    companion object {
+        /** Parse a persisted value; unknown/blank falls back to the default. */
+        fun fromName(name: String): ToolDetail =
+            entries.firstOrNull { it.name.equals(name, ignoreCase = true) } ?: TRUNCATED
+    }
 }