fix(i18n): mop up 4 remaining hardcoded strings in stats/run/sessions

[Evan-Pycraft]

Summary

补漏 4 处 CLI 硬编码字符串。

CLI (3 files):

• stats.ts — 两条 CLI 用法提示改用 t()
• run.ts — API key 缺失提示改用 t()，MCP hint 复用已有 key
• sessions.ts — 空会话提示改用 t()

i18n:

• src/i18n/EN.ts + zh-CN.ts: +3 sections (stats, run, sessions), 4 keys

Test plan

• npm run lint — clean
• npx tsc --noEmit — clean
• grep -rn 'run \\\\reasonix\|no saved sessions' src/cli/commands/` — clean

[esengine]

Thanks — the rest is exactly the kind of mop-up I want.

One small thing on the MCP reuse: mcpLifecycle.failedSetupConfigHint already starts with → (see EN.ts:1535), and the new template in run.ts still prefixes → ${t(...)} — rendered output ends up as → → run \reasonix setup`…. Drop the →from the template (keep just\n ${t("mcpLifecycle.failedSetupConfigHint")}\n`) and the line matches the pre-PR output exactly.

Otherwise good to merge.

[Evan-Pycraft]

Merged into #945 (combined CLI + dashboard i18n)