Bug Report: Absolute path on assets and links

[lifehome]

Describe the bug

If the subspace instance is running behind a reverse proxy under a subdirectory, such as https://example.org/subspace/, the application will attempt to source the static assets from https://example.org/static/... instead of https://example.org/subspace/static/..., links and buttons will also goes to the root directory(https://example.org/logout) as well.

This is due to the hard coded absolute path inside the web templates, and can be rectified by prepending the SUBSPACE_BACKLINK variable value back into the web template.

Note: The current "Subspace" text, which sits next to the home icon on the navigation bar, is a great example demonstrating the hard coded absolute path issue.

Proposed solution

Referencing to this line:

subspace/web/templates/header.html

Line 25 in 32fd13b

<a class="item" href="{{.Backlink}}"><i class="home icon"></i></a>

And also these lines with absolute path issues:

subspace/web/templates/header.html

Lines 8 to 18 in 32fd13b

	<link rel="icon" href="/static/favicon.png?v={{$.Version}}">
	<link rel="apple-touch-icon" href="/static/favicon.png?v={{$.Version}}">
	<title>Subspace</title>
	<link rel="stylesheet" type="text/css" href="/static/semantic/semantic.min.css?v={{$.Version}}">
	<link rel="stylesheet" type="text/css" href="/static/style.css?v={{$.Version}}">
	<link rel="stylesheet" type="text/css" href="/static/roboto.css?v={{$.Version}}">
	<script src="/static/jquery.min.js?v={{$.Version}}"></script>
	<script src="/static/semantic/semantic.min.js?v={{$.Version}}"></script>

It can be resolved by simply prepending the backlink template variable, for example

        <link rel="icon" href="{{.Backlink}}/static/favicon.png?v={{$.Version}}">
        <link rel="apple-touch-icon" href="{{.Backlink}}/static/favicon.png?v={{$.Version}}">

        <title>Subspace</title>

        <link rel="stylesheet" type="text/css" href="{{.Backlink}}/static/semantic/semantic.min.css?v={{$.Version}}">
        <link rel="stylesheet" type="text/css" href="{{.Backlink}}/static/style.css?v={{$.Version}}">
        <link rel="stylesheet" type="text/css" href="{{.Backlink}}/static/roboto.css?v={{$.Version}}">

        <script src="{{.Backlink}}/static/jquery.min.js?v={{$.Version}}"></script>
        <script src="{{.Backlink}}/static/semantic/semantic.min.js?v={{$.Version}}"></script>

To Reproduce

Steps to reproduce the behavior:

1. Run a subspace instance
2. Reverse proxy it behind nginx/swag/traefik/etc
3. Browse the corresponding URL of the web server, which is a proxy to the subspace instance
4. See the errors happen inside the browser console/inspector

Expected behavior

The assets and navigation links/buttons should be prepended with the backlink variable value.

Screenshots

Additional context

Sorry that I don't have time to make a PR at the very moment. However, if this issue isn't getting a fix within a week, I might squeeze some time to fix it.

[lifehome]

Okey so I was going on making a PR but found that other than the template strings, the Golang files also redirects pages with absolute path... Gotta find a workaround for that.