QR当てクイズの改良

[hakatashi]

• 実績をいくつか追加
• 回答時間を表示
• hard問題の出題時のバグ修正
• クソデカimageがsandboxにpostされないように修正
• isUnmasked => masked
• kanjiモードで漢字だけを出題するよう修正

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (b4a00c7) 23.56% compared to head (5757f77) 23.57%.

:exclamation: Current head 5757f77 differs from pull request most recent head 07ba8e9. Consider uploading reports for the commit 07ba8e9 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #822 +/- ## ======================================= Coverage 23.56% 23.57% ======================================= Files 167 167 Lines 14952 14968 +16 Branches 3400 3405 +5 ======================================= + Hits 3524 3528 +4 - Misses 10055 10067 +12 Partials 1373 1373 ``` | [Impacted Files](https://codecov.io/gh/tsg-ut/slackbot/pull/822?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tsg-ut) | Coverage Δ | | |---|---|---| | [achievements/achievements.ts](https://codecov.io/gh/tsg-ut/slackbot/pull/822?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tsg-ut#diff-YWNoaWV2ZW1lbnRzL2FjaGlldmVtZW50cy50cw==) | `100.00% <ø> (ø)` | | | [qrcode-quiz/index.ts](https://codecov.io/gh/tsg-ut/slackbot/pull/822?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tsg-ut#diff-cXJjb2RlLXF1aXovaW5kZXgudHM=) | `0.00% <0.00%> (ø)` | | ... and [2 files with indirect coverage changes](https://codecov.io/gh/tsg-ut/slackbot/pull/822/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tsg-ut)

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