Moves the NiceDiff type to the shared types package.

This now allows for a more organized template structure. All templates
can now be accessed via "parent/child" paths, and are templated atop
the layouts/*.html files.

The layout files themselves are modular and can be included in each
other. The only caveat is layout/*.html NEED to define their own
template names like so:

{{ define "base" }}

The other page templates do not (and musn't) define their own template.

This reverts commit 4d8e06b62e423f07df5623af237973e9a4384b7a.

This is for keyfetch use.

fetch keys like gh.com/user.keys

If last time_us is older than a week, we discard it and start over.
This also refreshes the saved last time_us in the database.

As much as possible. The atproto libs aren't themselves consistent about this.

* lexicon: add sh.tangled.knot.policy

* i ran lexgen

* i ran nix fmt

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Co-authored-by: Akshay <nerdy@peppe.rs>

use custom roundtripper for hmac signing

full registration flow works now