Build 8: stability fixes, Cash App-style shell, settings, key rotation

Stability (found via GUI testing):
- tor: create arti runtime on a clean thread; lazy TOR_STATE init panicked
  inside tokio contexts and poisoned the whole Tor/nostr stack
- store: open rkv SafeMode envs with capacity headroom; reopening at
  exactly DEFAULT_MAX_DBS crashed every wallet restart (DbsFull)
- goblin ui: centered_column hands children a full-height rect; ScrollAreas
  inside clipped everything below the first widget
- build: webtunnel client was silently embedded as 0 bytes without Go;
  warn at build, extract with create_dir_all + exec bit at runtime
- price: CoinGecko requires a User-Agent (403 otherwise); add retry-once
  backoff and a parse-failure diagnostic
- tor: retry http_request up to 3x on fresh isolated circuits

UX overhaul (per owner direction + Cash App references):
- floating icon-only 3-tab pill: Wallet / center accent ツ Pay puck /
  Activity (requests badge kept); Me opens via header avatar
- Pay tab: amount-first surface (numpad on mobile, typed on desktop) with
  Request and Pay; Pay carries the amount straight to Review
- Request flips Receive into "Requesting Nツ" state with a clear chip
- full-bleed goblin surface: GRIM title panel and network column hidden
  while a wallet is open; node status card lives in the sidebar above the
  profile chip; Lock wallet row added (Settings -> Wallet)
- goblin branding: titlebar, wallet-list logo + GOBLIN, new mark assets
  (white master, theme-tinted) in wordmark, QR center, wallet list
- build-based versioning: Build N = commits since the GRIM fork base,
  emitted by build.rs; About leads with it, Third party credits GRIM,
  grin node, nostr-sdk, arti, egui and the implemented NIPs

Accessibility & settings:
- surface_text{,_dim,_mute} tokens: yellow theme has dark cards on a
  bright bg; all on-surface text now readable in every theme (incl. QR)
- settings rows clickable across the whole row; profile card fills width;
  density option removed (comfy fixed)
- editable Node connections (integrated/external, add/remove) and Relays
  (add/remove + live service restart); NIPs explainer page with goblin.st
  context; third-party rows link to upstream projects
- standardized npub truncation (head 12 ... tail 6) shown in profile

Identity (owner decision: drop NIP-06 seed binding):
- random standalone nsec (Keys::generate); seed proves nothing about the
  identity and cannot resurrect it; legacy Derived identities still unlock
- key rotation: double warning (pending payments disrupted), typed RESET +
  wallet password, fresh random key, username moved atomically via the
  name server transfer endpoint; aborts cleanly if the move fails
- encrypted identity backup export (NIP-49 ncryptsec JSON, includes
  username + history) and import accepting nsec or backup JSON
- nip05d: POST /api/v1/transfer (NIP-98 by current owner, atomic
  owner-guarded swap, one-name-per-pubkey enforced) + SQL invariant tests

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/http/price.rs

@@ -29,8 +29,13 @@ lazy_static! {
 	static ref RATE: RwLock<Option<(f64, i64)>> = RwLock::new(None);
 	static ref FETCHING: std::sync::atomic::AtomicBool =
 		std::sync::atomic::AtomicBool::new(false);
+	static ref LAST_TRY: std::sync::atomic::AtomicI64 = std::sync::atomic::AtomicI64::new(0);
 }
 
+/// Minimum delay between fetch attempts, so a failing fetch (e.g. Tor still
+/// bootstrapping) does not respawn a thread every frame.
+const RETRY_SECS: i64 = 30;
+
 fn now() -> i64 {
 	SystemTime::now()
 		.duration_since(UNIX_EPOCH)
@@ -58,9 +63,14 @@ pub fn grin_usd_rate() -> Option<f64> {
 /// Spawn a background refresh over Tor (deduplicated).
 fn trigger_refresh() {
 	use std::sync::atomic::Ordering;
+	let t = now();
+	if t - LAST_TRY.load(Ordering::SeqCst) < RETRY_SECS {
+		return;
+	}
 	if FETCHING.swap(true, Ordering::SeqCst) {
 		return;
 	}
+	LAST_TRY.store(t, Ordering::SeqCst);
 	std::thread::spawn(|| {
 		let rt = tokio::runtime::Builder::new_current_thread()
 			.enable_all()
@@ -80,7 +90,18 @@ fn trigger_refresh() {
 async fn fetch_rate() -> Option<f64> {
 	let url =
 		"https://api.coingecko.com/api/v3/simple/price?ids=grin&vs_currencies=usd".to_string();
-	let body = Tor::http_request("GET", url, None, vec![]).await?;
-	let doc: serde_json::Value = serde_json::from_str(&body).ok()?;
-	doc.get("grin")?.get("usd")?.as_f64()
+	// CoinGecko rejects requests without a User-Agent (403). A static,
+	// non-identifying UA is fine over Tor.
+	let headers = vec![("User-Agent".to_string(), "goblin-wallet".to_string())];
+	let body = Tor::http_request("GET", url, None, headers).await?;
+	let parsed: Option<f64> = serde_json::from_str::<serde_json::Value>(&body)
+		.ok()
+		.and_then(|doc| doc.get("grin")?.get("usd")?.as_f64());
+	if parsed.is_none() {
+		log::warn!(
+			"price: unexpected response from rate API (Tor exit blocked?): {}",
+			body.chars().take(120).collect::<String>()
+		);
+	}
+	parsed
 }