fix(app): source composer cwd from agent state, not draft hook

The GitHub picker showed "No results found." for any running agent after
the first message was sent. useAgentInputDraft owned a local cwd state
that clear("sent") wiped to "", so the composer read cwd: "" even though
the agent's real cwd was correct on the wire.

Drop cwd ownership from the hook. Composer takes cwd as a prop sourced
by the parent — agentState.cwd for running agents, composerState.workingDir
for drafts, sourceDirectory for setup flows. The hook now persists only
{text, attachments}. Legacy persisted drafts with a cwd field still
hydrate; tagged COMPAT(draft-cwd) for removal after 2026-11-09.

Also moves attachment pills back inside the composer's bordered surface
via a new attachmentSlot prop on MessageInput, and shrinks pill height
from 48 to 32 — the subagents-track tuck previously had attachments
floating between it and the input.

Adds one Playwright spec asserting the draft-create-agent path submits
the workspace cwd.

packages/app/src/components/message-input.tsx

@@ -125,6 +125,8 @@ export interface MessageInputProps {
   onHeightChange?: (height: number) => void;
   /** Extra styles merged onto the input wrapper (e.g. elevated background). */
   inputWrapperStyle?: import("react-native").ViewStyle;
+  /** Content rendered inside the bordered input surface, above the text input (e.g. attachment pills). */
+  attachmentSlot?: React.ReactNode;
 }
 
 export interface MessageInputRef {
@@ -1094,6 +1096,7 @@ interface ResolvedMessageInputProps {
   onFocusChange: ((focused: boolean) => void) | undefined;
   onHeightChange: ((height: number) => void) | undefined;
   inputWrapperStyle: import("react-native").ViewStyle | undefined;
+  attachmentSlot: React.ReactNode;
 }
 
 function resolveMessageInputProps(props: MessageInputProps): ResolvedMessageInputProps {
@@ -1133,6 +1136,7 @@ function resolveMessageInputProps(props: MessageInputProps): ResolvedMessageInpu
     onFocusChange: props.onFocusChange,
     onHeightChange: props.onHeightChange,
     inputWrapperStyle: props.inputWrapperStyle,
+    attachmentSlot: props.attachmentSlot,
   };
 }
 
@@ -1180,6 +1184,7 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
       onFocusChange,
       onHeightChange,
       inputWrapperStyle,
+      attachmentSlot,
     } = resolveMessageInputProps(props);
     const buttonIconSize = isWeb ? ICON_SIZE.md : ICON_SIZE.lg;
     const toast = useToast();
@@ -1697,6 +1702,7 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
       <View ref={rootRef} style={styles.container} testID="message-input-root">
         {/* Regular input */}
         <Animated.View ref={inputWrapperRef} style={inputWrapperCombinedStyle}>
+          {attachmentSlot}
           {/* Text input */}
           <View style={styles.textInputScrollWrapper}>
             <ThemedTextInput