Add magic link auth

[dcramer]

Still some work to do here to make the flow have the user experience I want.

[codecov]

Codecov Report

Attention: Patch coverage is 70.89947% with 55 lines in your changes missing coverage. Please review.

Project coverage is 75.40%. Comparing base (fd91ffa) to head (ef17c35).
Report is 1 commits behind head on main.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
apps/server/src/lib/email.ts	20.45%	35 Missing ⚠️
apps/server/src/lib/auth.ts	5.88%	16 Missing ⚠️
...pps/server/src/trpc/routes/authMagicLinkConfirm.ts	95.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #225      +/-   ##
==========================================
- Coverage   75.62%   75.40%   -0.23%     
==========================================
  Files         300      303       +3     
  Lines       17882    18051     +169     
  Branches     1937     1950      +13     
==========================================
+ Hits        13524    13611      +87     
- Misses       4358     4440      +82     

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