Fix DB lock error: clear message + instructions, fix passphrase reprompt

Storage:
- Detects sled lock contention, shows actionable error:
  "Database locked by another warzone process"
  with ps command to find the process and rm command to force unlock

TUI:
- Poll loop no longer calls load_seed() (was re-prompting passphrase)
- Seed passed from main.rs to run_tui to poll_loop
- Single passphrase prompt per app launch

Warnings fixed:
- Removed unused `Context` import in tui/app.rs
- Added #[allow(dead_code)] on validate_token (used when auth middleware wired)

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

warzone/crates/warzone-server/src/routes/auth.rs

@@ -172,6 +172,8 @@ async fn verify_challenge(
 }
 
 /// Validate a bearer token. Returns the fingerprint if valid.
+/// Used by protected endpoints (will be wired in when auth middleware is added).
+#[allow(dead_code)]
 pub fn validate_token(db: &sled::Tree, token: &str) -> Option<String> {
     let data = db.get(token.as_bytes()).ok()??;
     let val: serde_json::Value = serde_json::from_slice(&data).ok()?;