feat(mesh-ui): reply banner + inline reaction chips (Phase 2a)

Tap a bubble to open an action menu with Reply + 6 quick reactions.
Reply stashes the target MessageKey and flips the Send button to
"Reply" mode, routing through mesh.send-reply. Reactions call
mesh.send-reaction immediately and render as chips under the target
bubble, collapsed per emoji with a count and self-highlight. Reaction
messages are filtered out of the main chat stream so they don't create
standalone bubbles. Reply bubbles show a "↳ quoted snippet" header
when the target is still in the local window.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

neode-ui/src/stores/mesh.ts

@@ -48,6 +48,8 @@ export type MeshMessageTypeLabel =
   | 'lightning_relay'
   | 'lightning_relay_response'
   | 'content_ref'
+  | 'reply'
+  | 'reaction'
 
 export interface MeshMessage {
   id: number
@@ -61,6 +63,10 @@ export interface MeshMessage {
   message_type?: MeshMessageTypeLabel
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   typed_payload?: Record<string, any> | null
+  /// Cross-transport identity for this message — (sender_pubkey, sender_seq)
+  /// forms a stable MessageKey used by replies/reactions.
+  sender_pubkey?: string | null
+  sender_seq?: number | null
 }
 
 export interface InvoiceData {
@@ -394,6 +400,34 @@ export const useMeshStore = defineStore('mesh', () => {
     }
   }
 
+  async function sendReply(contactId: number, targetPubkey: string, targetSeq: number, text: string) {
+    sending.value = true
+    try {
+      const res = await rpcClient.call<{ sent: boolean; message_id: number; sender_seq: number }>({
+        method: 'mesh.send-reply',
+        params: { contact_id: contactId, target_pubkey: targetPubkey, target_seq: targetSeq, text },
+      })
+      if (res.sent) await fetchMessages()
+      return res
+    } finally {
+      sending.value = false
+    }
+  }
+
+  async function sendReaction(contactId: number, targetPubkey: string, targetSeq: number, emoji: string) {
+    try {
+      const res = await rpcClient.call<{ sent: boolean; message_id: number; sender_seq: number }>({
+        method: 'mesh.send-reaction',
+        params: { contact_id: contactId, target_pubkey: targetPubkey, target_seq: targetSeq, emoji },
+      })
+      if (res.sent) await fetchMessages()
+      return res
+    } catch (err: unknown) {
+      error.value = err instanceof Error ? err.message : 'Failed to send reaction'
+      throw err
+    }
+  }
+
   async function fetchContent(params: {
     cid: string
     sender_onion: string
@@ -530,6 +564,8 @@ export const useMeshStore = defineStore('mesh', () => {
     sendAlert,
     sendContent,
     fetchContent,
+    sendReply,
+    sendReaction,
     getSessionStatus,
     rotatePrekeys,
     getNodePositions,