fix(diagnostics): address adversarial review of the QoL UI (popup, staleness, DPI, i18n)

Follow-up to the node-banner / staleness-badge / alert-history features — a 5-dimension
finder->verify review surfaced 4 real issues (the ImGui-stack-balance finder found none):

- Alert popup grew off the right edge: pivot (0,1) pinned the panel's LEFT edge at the
  bell, which sits near the window's right edge, so a 320px panel overflowed rightward
  (an explicit SetNextWindowPos pivot skips ImGui's on-screen clamp). Anchor the
  bottom-RIGHT corner at the bell instead (pivot (1,1) at bellMax.x) so it grows left.

- Staleness badge could flash red on reconnect: WalletState::clear() reset everything
  except the four last_*_update stamps, so the pre-outage timestamp survived and the
  badge briefly showed "Updated Nm ago" the same frame the node banner cleared. Zero the
  stamps in clear() (all readers treat 0 as "never"; app_network.cpp:1473 guards != 0).

- Banner min-height floor wasn't DPI-scaled: std::max(minH, baseH*vScale()) now uses
  minH * dpiScale() so both operands are in scaled px.

- New i18n keys weren't in res/lang/: back-filled all 16 diagnostics/QoL keys into the 8
  language files, additively (128 insertions, 0 deletions). zh/ja/ko reworded around 2
  glyphs missing from the CJK subset and hard-asserted tofu-free against the subset font.

Build-clean both variants; ctest 1/1.

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

docs/wallet-hardening.md

@@ -112,6 +112,11 @@ Land W7-2 first — it unblocks the rest.
 
 ## Progress log
 
+- **Adversarial review of the 3 diagnostics UI features** — ran a 5-dimension finder → per-finding verify workflow over the node-banner + staleness-badge + alert-history commits (the hand-laid ImGui I couldn't visually verify). 4 confirmed, 1 refuted (banner title never overlaps its button — button is absolutely positioned + title is short), and the dedicated ImGui-stack-balance finder found **no** Push/Pop imbalance. Fixes landed:
+  - **(Med) Alert popup grew off the right edge** — pivot `(0,1)` pinned the panel's *left* edge at the bell (which sits near the window's right edge), so a 320px panel overflowed rightward (an explicit `SetNextWindowPos` pivot skips ImGui's on-screen clamp). Fixed to anchor the bottom-*right* corner at the bell (pivot `(1,1)`, at `bellMax.x`) so it grows left over the canvas.
+  - **(Low) Staleness badge could flash red on reconnect** — `WalletState::clear()` reset everything *except* the four `last_*_update` stamps, so after a reconnect the pre-outage timestamp survived and the badge briefly showed "Updated Nm ago" (red) on the same frame the node banner cleared — the exact contradiction the design forbids. Fixed by zeroing the four stamps in `clear()` (all readers treat 0 as "never"; verified `app_network.cpp:1473` guards on `!= 0`).
+  - **(Low) Banner min-height floor wasn't DPI-scaled** — `std::max(minH, baseH*vScale())` compared a raw-px floor against a scaled value; now `minH * dpiScale()`.
+  - **(Low) New i18n keys weren't in `res/lang/`** — back-filled all 16 diagnostics/QoL keys (this session's node_banner_*/data_stale_*/alerts_*/settings_*/tt_*) into all 8 language files, additively (128 insertions, 0 deletions). zh/ja/ko reworded around 2 glyphs missing from the CJK subset (提醒→通知; ko tooltip avoids 닐) and hard-asserted tofu-free against the subset font.
 - **Foundation QoL / Persistent alert history** — ☑ landed. Toasts fade in 1–4s; there was no way to review what scrolled past. `Notifications` now retains every pushed alert in a capped (100) ring buffer with a wall-clock epoch (`AlertRecord`) — separate from the 5-item live-toast deque — plus a monotonic `total_pushed_` counter. A bell in the status-bar right cluster (`ICON_MD_NOTIFICATIONS`) opens an upward popup listing recent alerts newest-first with a severity icon/colour (reusing the toast palette), the message, and a relative age (`formatTimeAgoShort`), with a Clear-all action. An **unread dot** on the bell (coloured by the most-severe unseen alert) marks alerts that arrived since the panel was last opened — driven by `totalPushed()` deltas so it survives capping/clearing. Thread-safety: every push is on the UI thread (RPC results run as main-thread `MainCb`s), matching the class's existing lock-free model — documented as a no-raw-worker-thread invariant. Build-clean; `ctest` 1/1 (adds `testNotificationHistory`: retention, order, cap, monotonic counter, clear). **This closes the QoL bundle and the Foundation tier.**
 - **W6-2 / Refresh-staleness badge** — ☑ landed. The Total Balance card now shows a small pill on its status line ("Updated 2m ago", amber → red past 3 min) **only when connected but the balance stopped refreshing** — a busy daemon can fail `z_gettotalbalance` without dropping the whole connection (only *both* core RPCs failing 3× triggers a disconnect), leaving stale numbers on screen while the node-status banner stays hidden. No refresh-path changes were needed: `WalletState::last_balance_update` is already stamped only on a successful fetch (`network_refresh_service.cpp:1187`), so the badge just reads it and computes age against the same `std::time` clock (`util::formatTimeAgoShort`). Decision is a pure, unit-tested helper (`ui/staleness_badge.h::evaluateStalenessBadge`, thresholds 45s/180s) gated on `connected` so it never contradicts the banner; hover shows a "may be out of date — check your node connection" tooltip. Build-clean; `ctest` 1/1 (adds `testStalenessBadge`). **This closes P2 (5/5).**
 - **Foundation QoL / Persistent node-status banner** — ☑ landed. A persistent horizontal strip now sits at the top of the content column whenever the wallet can't reach its node — distinct from the transient toasts, so an offline wallet is never silently mistaken for a working one. The show/severity/action decision is a pure function (`ui/node_status_banner.h` → `evaluateNodeStatusBanner`, unit-tested) fed a state snapshot by `App::renderNodeStatusBanner()`. Three cases: **full-node offline** (amber, "Reconnect" → `tryConnect`), **embedded daemon crashed & auto-restart gave up** (red, "Restart node" → `restartDaemon`), **lite wallet failed to open** (red, message-only). Suppressed during the wizard / wallet-switch / daemon-restart / screenshot-sweep / shutdown, and while an expected startup phase (warmup/init/connect-in-progress) already owns the screen. Height in `res/themes/ui.toml` (`banners.node-status`); colours from the material semantic palette; detail text ellipsis-clipped so it can't shove the action button off-screen. Build-clean; `ctest` 1/1 (added `testNodeStatusBanner`). **Remaining QoL:** persistent alert history, and the W6-2 refresh-staleness badge.