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/composer.tsx

@@ -1541,7 +1541,6 @@ export function Composer({
 
           <View style={styles.messageInputContainer}>
             {autocompletePopover}
-            {attachmentPreviewList}
 
             {/* MessageInput handles everything: text, dictation, attachments, all buttons */}
             <StableMessageInput
@@ -1581,6 +1580,7 @@ export function Composer({
               onFocusChange={handleFocusChange}
               onHeightChange={onComposerHeightChange}
               inputWrapperStyle={inputWrapperStyle}
+              attachmentSlot={attachmentPreviewList}
             />
             <Combobox
               options={githubSearchOptions}
@@ -1685,16 +1685,16 @@ const styles = StyleSheet.create((theme: Theme) => ({
     flexWrap: "wrap",
   },
   imageThumbnail: {
-    width: 48,
-    height: 48,
+    width: 32,
+    height: 32,
   },
   imageThumbnailPlaceholder: {
-    width: 48,
-    height: 48,
+    width: 32,
+    height: 32,
     backgroundColor: theme.colors.surface2,
   },
   githubPillBody: {
-    minHeight: 48,
+    minHeight: 32,
     maxWidth: 260,
     flexDirection: "row",
     alignItems: "center",