fix: Tier-2 mediums — input trims, confirmations, amount normalization

More robustness fixes from the audit (the import-key pattern, lower severity):

- Trim pasted input before use/validation: network add-server URL/label,
  lite-wallet key import (+ block empty), validate-address, address-book entry.
- Confirmations for destructive/irreversible actions:
  - Address-book Delete now needs a confirming second click (no undo).
  - Console `stop` needs a confirming second `stop` (it shuts down the node).
  - Wizard "Skip" encryption needs a confirming second click (keys stored
    unencrypted).
- Send amount: normalize to 8dp (satoshi precision) on both the DRGX and USD
  inputs so digits past 8dp aren't silently dropped between the preview/review
  and what's actually sent.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/ui/windows/validate_address_dialog.cpp

@@ -80,7 +80,10 @@ void ValidateAddressDialog::render(App* app)
             s_error_message.clear();
             
             std::string address(s_address_input);
-            
+            // Trim whitespace/newlines a pasted address often carries (the daemon would reject it).
+            while (!address.empty() && (address.front()==' '||address.front()=='\t'||address.front()=='\n'||address.front()=='\r')) address.erase(address.begin());
+            while (!address.empty() && (address.back()==' '||address.back()=='\t'||address.back()=='\n'||address.back()=='\r')) address.pop_back();
+
             // Determine if z-address or t-address
             bool is_zaddr = !address.empty() && address[0] == 'z';