fix(audit): batch 1 — latent unlock/path/rescan correctness bugs

Four correctness fixes surfaced by the codebase audit:

1. Lite address-book path bug: AddressBook::getDefaultPath() hardcoded
   "ObsidianDragon" while Settings::getDefaultPath() uses DRAGONX_APP_NAME,
   so the Lite build wrote addressbook.json into the full-node app's config
   dir instead of ObsidianDragonLite/. Now uses DRAGONX_APP_NAME on all
   platforms (no macOS path change — the getConfigDir consolidation, which
   would move the macOS dir, is deferred).

2. PIN-unlock lockout bypass: the PIN path duplicated unlockWallet's
   success/lockout logic and its RPC-error branch bumped the attempt counter
   but skipped the escalating-lockout math entirely — a PIN user hitting an
   RPC error escaped the lockout curve. Extracted App::applyUnlockSuccess()
   and App::applyUnlockFailure() and routed all unlock paths (passphrase,
   PIN vault-fail, PIN RPC-fail) through them, so the lockout curve now
   applies uniformly. (noVault stays a mode-switch, not a failed attempt.)

3. Witness/rescan reset drift: the ~11-line rescan+witness completion reset
   was copy-pasted at four sites (app.cpp x2, app_network.cpp x2); adding a
   witness field and missing a copy would leave stale progress. Folded into
   App::resetWitnessRescanProgress(). Left the distinct phase-transition
   reset in App::update() untouched (it sets witness_phase, not 0).

4. Truncation underflow: send_tab/receive_tab's size_t TruncateAddress
   copies computed (maxLen - 3) without guarding maxLen <= 3, which wraps
   and throws std::out_of_range on short inputs. Added the guard.

Full-node + Lite build clean; ctest 1/1; source-hygiene clean.

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

src/app.h

@@ -473,6 +473,14 @@ private:
     std::string transactionHistoryCacheWalletIdentity() const;
     bool ensureTransactionHistoryCacheUnlockedFor(const std::string& walletIdentity);
     void unlockTransactionHistoryCacheWithPassphrase(const std::string& passphrase);
+    // Shared main-thread continuations for a wallet unlock attempt, so the passphrase
+    // and PIN paths cannot drift. applyUnlockFailure applies the escalating lockout
+    // curve on every failed path (a PIN RPC failure used to skip it).
+    void applyUnlockSuccess(const std::string& passphrase, int timeout);
+    void applyUnlockFailure(const std::string& errorMessage);
+    // Clear all rescan + witness-rebuild progress/accumulator state. Shared by the four
+    // rescan-completion sites so a new witness field can't be forgotten in one copy.
+    void resetWitnessRescanProgress();
     void loadTransactionHistoryCacheIfAvailable();
     void storeTransactionHistoryCacheIfAvailable();
     void wipePendingTransactionHistoryCachePassphrase();