feat(ui): layout polish — fill dead space, pair/box/collapse, warning weight, dialog glass

Implements the layout-improvement suggestions from the layout audit (visual arrangement
only; no functionality added or removed):

- Send/Receive: the recent-activity list now grows to fill the space below the fixed
  compose/receive card (more history visible), with a centered empty-state when there is
  none — instead of leaving dead canvas.
- Shield/Merge: pair the Fee and UTXO-Limit fields on one row to tighten vertical rhythm.
- Market: extend + frame the portfolio group-list as one contained panel (with a bottom
  edge) and center its empty-state, closing the previously un-anchored gap.
- Overlay dialogs: raise the card glass fill/border alpha (35/50 -> 60/90 of 255) so the
  dialog card reads as a distinct surface over busy backdrops (global, all overlays).
- Wallets: size the list height to the actual wallet count instead of always reserving 7
  rows, removing the large gap before the scan/create prompts (still scrolls when many).
- Contacts: width-aware address truncation shows more of the address on wide rows.
- Transfer Funds: give the "sends the full balance" warning a warning icon + color so the
  stakes stand out from the neutral result-preview lines.
- First-run wizard: collapse a completed Step 1 (Appearance) to the compact pill like
  Step 2, so a finished step is no longer taller than the active one.
- Explorer: distribute the Chain card's two stats to match the density of the sibling
  metrics grid.
- Validate Address: a "Results will appear here" caption fills the pre-interaction blank.
- Change Passphrase: add the warning banner its sibling security dialogs have.
- Migration ShowSeed: box the 24-word mnemonic grid (a GlassSectionScope behind the
  existing RenderSeedWordGrid) so the critical secret reads as a distinct artifact —
  purely visual, no seed/logic/state change.

Verified at 1280 across full-node + Lite + Windows (ctest green) and an adversarial diff
review (clean). New i18n key backfilled into all 8 languages.

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

res/lang/ja.json

@@ -1669,6 +1669,7 @@
     "validate_not_mine": "このウォレットに属していません",
     "validate_ownership": "所有者：",
     "validate_results": "結果：",
+    "validate_results_placeholder": "ここに結果が表示されます",
     "validate_shielded_type": "シールド（zアドレス）",
     "validate_status": "ステータス：",
     "validate_title": "アドレスを検証",
@@ -1827,4 +1828,4 @@
     "your_addresses": "あなたのアドレス",
     "z_address": "Zアドレス",
     "z_addresses": "Zアドレス"
-}
+}