fix(mining): make "Est. Daily" honest about variance and fees

The mining "Est. Daily" was a solo expected-value (your hashrate share x
blocks/day x a fixed block reward) rendered in the same green as the real
Today / Yesterday / All-Time earnings, off an instantaneous hashrate and
gross of pool fees. It read like a dependable daily income when it is a
long-run statistical average with huge (Poisson) variance.

Framing:
- The estimate is now drawn in a neutral colour, not the green "money
  earned" colour (the actual mined totals stay green).
- A sub-label in BOTH modes marks it as an average ("avg", or "avg, net"
  in pool mode when the fee is applied), replacing the pool-only
  "before pool fee" note.
- A hover tooltip over the column explains the variance ("often nothing
  for long stretches, then a lump - NOT a steady daily income") and the
  fee status (after the N% fee / before the fee when unknown / nothing for
  solo and 0%-fee pools).

Accuracy:
- Uses a trailing-average hashrate instead of the instantaneous / 10s
  snapshot: pool prefers hashrate_15m (then 60s, then 10s); solo uses the
  mean of hashrate_history once there are >=10 samples, else the instant
  rate. This stops a spike or a momentary dip from swinging the figure.
- Subtracts the known pool fee so pool-mode figures are net; synthetic or
  unmatched pools stay gross and the tooltip says the fee is unknown.

The static block reward and true pool-reported earnings are intentionally
out of scope (the latter needs a new pool-API field). New i18n keys are
translated into all eight locales; the CJK subset font is rebuilt for the
three new glyphs. Builds + test suites pass on both variants.

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

res/lang/ja.json

@@ -1308,6 +1308,8 @@
     "mining_est_block": "予測ブロック",
     "mining_est_daily": "予測日収",
     "mining_est_daily_pool_sub": "おおよそのソロ換算（プール手数料前）",
+    "mining_est_daily_sub": "平均",
+    "mining_est_daily_sub_net": "平均・手取り",
     "mining_filter_all": "すべて",
     "mining_filter_tip_all": "すべての収益を表示",
     "mining_filter_tip_pool": "プール収益のみ表示",
@@ -2108,6 +2110,9 @@
     "tt_low_spec": "すべての重い視覚効果を無効化\\nホットキー：Ctrl+Shift+Down",
     "tt_merge": "複数の UTXO を一つのアドレスに統合",
     "tt_mine_idle": "システムがアイドル状態（キーボード/マウス入力なし）\\nのとき自動的にマイニングを開始",
+    "tt_mining_est_daily": "ネットワーク全体に占める現在のハッシュレート比率に基づく長期的な統計平均です。実際のマイニング報酬はランダム（ポアソン分布）に発生し、長期間ゼロが続いた後にまとまって得られることが多いため、これは安定した日次収入ではありません。",
+    "tt_mining_est_daily_fee_fmt": "%.1f%% のプール手数料を差し引いた値です。",
+    "tt_mining_est_daily_nofee": "プール手数料を差し引く前の値です（このプールの手数料は不明）。",
     "tt_new_mining_address": "ソロマイニング報酬用の透明（R…）アドレスを作成します。支払いは受け取れません。支払いにはシールドアドレスを共有してください。",
     "tt_noise": "グレインテクスチャ強度（0% = オフ、100% = 最大）",
     "tt_open_app_dir": "ObsidianDragon フォルダ（設定、テーマ、ログ）をファイルマネージャーで開く",