Bump version to v0.1.8 — Windows playtest fixes

- Fix switchAccount: check signer was set after loginWithNsec before
  returning; fall back to loginWithPubkey on silent failure; always
  navigate to feed after switch to clear stale UI
- Fix profile edit button: hidden in read-only (npub) mode; read-only
  badge shown in profile header to make state visible
- Sidebar: show version number (v0.1.8) below WRYSTR brand, auto-tracked
  from package.json — no more hardcoding
- Support page: increase QR code gap (gap-8 → gap-16) to prevent
  accidentally scanning the wrong address
- ROADMAP: add language/alphabet feed filter to Phase 3 backlog

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "Wrystr",
-  "version": "0.1.7",
+  "version": "0.1.8",
   "identifier": "com.hoornet.wrystr",
   "build": {
     "beforeDevCommand": "npm run dev",