feat(client): transaction detail screen (wallet history → tap to inspect)

Users can now tap any row in the wallet history and see the full
transaction detail, matching what the block explorer shows for the
same tx. Covers every visible activity — transfers, contact
requests, likes, posts, follows, relay proofs, contract calls.

Components

  lib/api.ts
    - New TxDetail interface mirroring node/api_explorer.go's
      txDetail JSON (id, type, from/to + their DC addresses, µT
      amount + display string, fee, block coords, gas, payload,
      signature hex).
    - getTxDetail(txID) with 404→null handling.

  app/(app)/tx/[id].tsx — new screen
    - Hero row: icon + type label + local-time timestamp
    - Big amount pill (only for txs that move tokens) — signed by
      the viewer's perspective (+ when you received, − when you
      paid, neutral when it's someone else's tx or a non-transfer)
    - Info card rows with tap-to-copy on hashes and addresses:
      Tx ID, From (highlighted "you" when it's the signed-in user),
      To (same), Block, Fee, Gas used (when > 0), Memo (when set)
    - Collapsible Payload section — renders JSON with 2-space
      indent if the node could decode it, otherwise the raw hex
    - Signature copy row at the bottom (useful for debugging / audits)
    - txMeta() covers all EventTypes from blockchain/types.go
      (TRANSFER, CONTACT_REQUEST/ACCEPT/BLOCK, REGISTER_KEY/RELAY,
      BIND_WALLET, RELAY_PROOF, BLOCK_REWARD, HEARTBEAT, CREATE_POST,
      DELETE_POST, LIKE_POST/UNLIKE_POST, FOLLOW/UNFOLLOW,
      CALL_CONTRACT, DEPLOY_CONTRACT, STAKE/UNSTAKE) with
      distinct icons + in/out/neutral tone.
    - Nested Stack layout so router.back() pops to the caller;
      safeBack() fallback when entered via deep link.

  app/(app)/wallet.tsx
    - TxTile's outer Pressable was a no-op onPress handler; now
      router.push(`/(app)/tx/${tx.hash}`). Entire row is the
      touch target (icon + type + addr + time + amount).

  app/(app)/_layout.tsx
    - /tx/* added to hideNav regex so the detail screen is
      full-screen without the 5-icon bar at the bottom.

Translation quirk

  The screen is English to match the rest of the UI (what the user
  just asked for in the previous commit). Handles copying via
  expo-clipboard — tapping an address/hash shows "Copied" for 1.5s
  with a green check, then reverts.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

client-app/app/(app)/_layout.tsx

@@ -36,10 +36,12 @@ export default function AppLayout() {
   //  - chat detail
   //  - compose (new post modal)
   //  - feed sub-routes (post detail, hashtag search)
+  //  - tx detail
   const hideNav =
     /^\/chats\/[^/]+/.test(pathname) ||
     pathname === '/compose' ||
-    /^\/feed\/.+/.test(pathname);
+    /^\/feed\/.+/.test(pathname) ||
+    /^\/tx\/.+/.test(pathname);
 
   useBalance();
   useContacts();