Add new download pgp key route

[danielemery]

• Moves existing pgp route /pgp.asc to /pgp
• Adds new /pgp/daniel_emery.pub.asc route with content disposition suggesting download

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (99f3691) 91.42% compared to head (de7bb55) 92.17%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #15 +/- ## ========================================== + Coverage 91.42% 92.17% +0.74% ========================================== Files 4 4 Lines 105 115 +10 Branches 18 20 +2 ========================================== + Hits 96 106 +10 Misses 9 9 ``` | [Files](https://app.codecov.io/gh/danielemery/keys/pull/15?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniel+Emery) | Coverage Δ | | |---|---|---| | [src/server.ts](https://app.codecov.io/gh/danielemery/keys/pull/15?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniel+Emery#diff-c3JjL3NlcnZlci50cw==) | `86.44% <100.00%> (+2.76%)` | :arrow_up: |

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