feat(lite): wire the create-time passphrase into the lite encrypt/unlock flow (W5-3)

The lite create/open/restore requests carried a passphrase field that the UI collected
(a labeled, masked "passphrase" input) but the backend initialize* calls never used —
so a user could believe their lite wallet was passphrase-protected at creation when it
did nothing. It now has a real meaning, wired in LiteWalletController:

- create / restore -> encryptWallet(passphrase): the backend encrypts + locks + saves
  the brand-new wallet.
- open -> unlockWallet(passphrase), but only when encryptionStatus() reports the existing
  wallet is actually encrypted + locked (no spurious unlock on an unencrypted wallet).

encryptWallet/unlockWallet take their own copy of the passphrase and wipe it; the
request copy is still wiped as before. A post-create encrypt failure is liteLog'd (the
wallet still exists, so the create is not failed).

Six existing lite-controller tests carried an incidental "hunter2" create passphrase from
when the field was dead; removed (they exercise non-encryption flows and want an
unencrypted wallet), and added testLiteWalletControllerCreateEncryptsWithPassphrase to
prove the new behavior. Completes the wallet-hardening P0-A cluster (7/7). ctest 1/1.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/wallet-hardening.md

@@ -16,7 +16,7 @@ Status legend: ☐ not started · ◐ in progress · ☑ landed & verified
 
 | Phase | Findings | Theme | Status |
 |-------|----------|-------|--------|
-| **P0-A** | W7-1, W2-1, W4-1, W4-3, W2-3, W4-5 ✓ · W5-3 ⚑ | Secret hardening (console redaction + delete-export + memzero) | ◐ 6/7 |
+| **P0-A** | W7-1, W2-1, W4-1, W4-3, W2-3, W4-5, W5-3 ✓ | Secret hardening (console redaction + delete-export + memzero + lite encrypt-at-create) | ☑ 7/7 |
 | **P0-B** | W2-2/W4-2, W2-4 | Encryption integrity (never silently unencrypted) | ☐ |
 | **P1-A** | W3-1, W3-2, W3-4, W3-3 | Migrate-to-seed correctness (fund-adjacent) | ☐ |
 | **P1-B** | W1-1, W1-3, W1-2, W1-4 | Missing/wrong wallet-file safety | ☐ |
@@ -112,7 +112,7 @@ Land W7-2 first — it unblocks the rest.
 
 ## Progress log
 
-- **P0-A / W5-3 (lite create-time passphrase)** — ⚑ **needs a product decision, not a speculative code change.** Investigation revised the finding: the passphrase field is already `secureWipeLiteSecret`'d on every path (controller:1175/1183/1192, settings_page:295), so the security exposure is minimal. The real issue is a **misleading UI**: `settings_page.cpp:1733-1739` renders a labeled, masked "passphrase" `InputText` at lite create/open/restore, but the backend `initialize*` calls (lifecycle_service:326/334/342) never consume it (lite encryption is a *separate* post-open `encrypt` flow). A user may believe their lite wallet is passphrase-protected at creation when it isn't. Two options, both product calls: **(a) remove** the dead field + its UI (settings_page 121/272/276/281/295/1733-1740, the request `passphrase` fields, the redaction/wipe refs), or **(b) wire** it into the lite `encrypt` flow so it actually protects the new wallet. Not changed unilaterally.
+- **P0-A / W5-3 (lite create-time passphrase)** — ☑ landed (chose option **(b) wire it up**). The lite create/open/restore passphrase was collected but never consumed by the backend — a "passphrase" field that did nothing. It now has a real meaning for all three operations, in `LiteWalletController`: **create/restore** → `encryptWallet(passphrase)` (the backend encrypts + locks + saves the brand-new wallet); **open** → `unlockWallet(passphrase)`, but only when `encryptionStatus()` reports the existing wallet is actually encrypted+locked (skips a spurious unlock otherwise). Encrypt/unlock take their own copy and wipe it; a post-create encrypt failure is `liteLog`'d (the wallet still exists — the create isn't failed). Six existing lite-controller tests carried an incidental `hunter2` create passphrase from the dead-field era; removed (they test non-encryption flows and want an unencrypted wallet), and added `testLiteWalletControllerCreateEncryptsWithPassphrase` to prove the new behavior. Build-clean; `ctest` 1/1. *(Follow-up UX polish: `settings_page` could show the passphrase field's meaning per operation — "encrypt" for create/restore vs "unlock" for open.)*
 - **P0-A / W4-5 (seed-backup file)** — ☑ landed (proportionate): the seed "Save" already wrote 0600 + zeroed the in-memory buffer, but the success message was a bare "Saved to <path>". It now reads "**Saved an UNENCRYPTED seed file — move it to secure offline storage and delete this copy**: <path>", so the plaintext-on-disk risk is called out. `i18n.cpp` (English source; `res/lang` back-fill of this changed key is deferred to the batch i18n pass). A stronger fix (pre-save confirmation, or dropping the file-save in favor of on-screen + Copy) is a follow-up UX decision.
 - **P0-A / W4-1 · W4-3 · W2-3 (memzero cluster)** — ☑ landed, using the file's established `sodium_memzero` pattern (matching the existing lambda-capture scrub at app_network.cpp:2885 and JSON scrub at :4025) rather than a new type, since this is fund-moving code:
   - **W4-1** `importPrivateKey`/`sweepPrivateKey`: the spending/viewing key is now scrubbed on all paths — the calling-frame copy (after the worker post), the worker-lambda's captured copy (lambda made `mutable`, zeroed after the request is sent), and the JSON request `params` copy.