bigger links

Adds 'x-tangled-repo-owner-handle' header when proxying git requests to
the knot. This allows knotserver to attempt to suggest the correct
git+ssh URL when rejecting a HTTP git push.

* Checks service name query parameter in info/refs handler; rejects any
service request that doesn't match 'git-upload-pack'.

* Produces 'text/plain' error responses so the git client will display
them.

* Adds a specific reject message for 'git-receive-pack'. This will
produce a less cryptic error in the terminal when trying to push over
http.

Sorts branches by update time (and in same-repo comparisons we drop the
default branch) and preselects the most recent branch.

empty repo template now shows a list of other branches if available

- setting default-branch now works on repos that have empty default
branches
- RepoIndex now returns branch-list if available on empty repos

This adds a post-processor step to the markdown parser to parse raw
html images `<img>` and resolve their `src` attributes if needed

This commit adds spinners to what I believe to be all the buttons on the
following pages:
- follow: add spinner to follow button
- issues/new: add spinner to create button
- issue: add spinners to close/reopen issue buttons
- issueComment: add spinner to delete button
- editIssueComment: add spinner to check mark button
- pulls/new: add spinner to create button
- pullNewComment: add spinner to comment button, submit and cancel
- pullResubmit: add spinners to resubmit / cancel button
- settings: add spinners to buttons
- knots: add spinners to buttons
- settings: add spinners to user settings page

Fixes a bug reported on Discord with relative links inside a
repository's subdir would resolve incorrectly since we were naively
"absoluting" the link destination.

Now, we resolve it against the current (parent) directory. For example,
if lol/x.md has a link

[foo](./some.png) => /lol/some.png (instead of just /some.png)

thanks @cinny.bun.how on bluesky.

also setup nix devshell to configure TANGLED_OAUTH_JWK in a shellhook
for seamless local oauth dev.

[preview](https://cdn.discordapp.com/attachments/1361968270516949092/1371809102023622699/image.png?ex=68247c48&is=68232ac8&hm=d743ac41cf52bdee418f3260a99860fad4ad11d2c105954e663dabf2735e18f3&)

the pull-id was extracted out of transaction

how it works:

- hx-indicator adds the htmx-request class to the target of choice
- with tailwind, we can use `group-[.class]` to check if a parent
element has a certain class, and style things conditionally
- by applying `group-[.htmx-request]`, we can detect when a request is
in progress, and show/hide a lucide loader
- the loader is a static icon made to spin using the `animate-spin`
class

setting TANGLED_DEV=true now lets you work on tangled without creating
ngrok/localtunnel tunnels.

NixOS 24.11 doesn't provide go-1.24 which is now required for this
project.

Additionally fix the `CGO_ENABLED` warnings that comes with the newer
nixpkgs version.