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### Description

<!-- Please include a summary of the change. Please also include
relevant motivation and context. List any dependencies that are required
for this change. -->

As I haven't really had any issues I'm not 100% sure this fixes anything
at all, but it at least doesn't break anything.

Increase the timeout for background clients to 60s, separates them into
their own store, and makes sliding sync respect the setting instead of
the client setting, and hopefully better management.

Adds a startup timeout of 45s to the main loading screen to prevent
anything from getting stuck behind that which may or may not actually do
anything.

Replaces the sdk's thread root event fetching on initial load to prevent
the useless loading delay and request spam on load. Get's swapped back
once the client loads which then functions normally, only loading thread
events when a room is opened.

Also some random formatting changes that happened in initMatrix.ts when
I saved for some reason?? They're more readable imo so I just left them
in.

Also fixed the 1 lint issue from #730 

Maybe related to #710 

#### Type of change

- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] This change requires a documentation update

### Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my own code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings

### AI disclosure:

- [x] Partially AI assisted (clarify which code was AI assisted and
briefly explain what it does).
- [ ] Fully AI generated (explain what all the generated code does in
moderate detail).
<!-- Write any explanation required here, but do not generate the
explanation using AI!! You must prove you understand what the code in
this PR does. -->

Bickered with an AI to diagnose some potential syncing issues but none
of the changes were directly AI written.

> [!IMPORTANT]
> Merging this PR will create a new release.

## Features

* Add background styling to user profile cards
([SableClient#712](SableClient#712) by @nushea)
* Add preventing url preview cards by surrounding a link in
anglebrackets like <https://app.sable.moe>
([SableClient#717](SableClient#717) by @nushea)
* Reorganize Embed settings and reintroduce multiple embeds
([SableClient#667](SableClient#667) by @nushea)
* Change Misc. data styling in users profile pages
([SableClient#663](SableClient#663) by @nushea)
* add initial support for sending discoverable emojis and sticker
([SableClient#730](SableClient#730) by @dozro)

### Themes and tweaks from the catalog
([SableClient#633](SableClient#633) by @7w1)

Themes are pulled from [a repo](https://github.com/SableClient/themes)
now, so you get the full power of CSS instead of a palette. Tweaks are
new: CSS overlays that sit on top of whatever theme you are using.

You'll be prompted to migrate to the new system whenever you update, if
you choose not to, you'll be limited to the basic dark/light themes. A
few additional themes have been added (Rose Pine variantes, Catpuccin)
along with some basic tweaks (circular avatars, monochrome avatars, and
square stuff).

You can share themes and tweaks. For themes uploaded online, simply hit
the copy button in settings and paste the link in chat. If the setting
is enabled, a preview will be generated. Third party themes (as defined
by the config.json) have prominent warning banners and fetching is
disabled by default.

You can also export and share theme files directly, although no previews
are generated for these.

If you're intrested in getting a theme or tweak added to the official
catalog, contribute to the themes repo linked above! We're eager to add
more!

### Markdown parser and render updates
([SableClient#727](SableClient#727) by @7w1)

Migrated markdown parsing and rendering to use marked, which should fix
most (all?) markdown issues involving lists/nested structures,
inconsistent/inaccurate code blocks, escape sequences, and all the other
bugs with literally everything.

Added math rendering support via marked and KaTeX, uses standard `$$`
and `$` delimiters. Only renders a subset of latex tags that will likely
need to be expanded so feel free to make issues if needed.

Also adds support for sending markdown tables (although they're rendered
rather plainly at the moment), sending valid html directly (such as for
colored text), and properly escaping anything with backslashes.

Fixes link previews appearing in code blocks, fixes pmp new line
behavior, fixes links not opening in new tabs, and fixes editing
arbitrary html messages, probably.

Finally, the old WYSIWYG editor has been completely removed.

## Fixes

* Fix spam-clicking abbreviations crashing sable
([SableClient#665](SableClient#665) by @nushea)
* Add cache-control headers in Caddyfile for assets, service worker, and
index.html ([SableClient#609](SableClient#609) by
@Just-Insane)
* Fix the first pin event in a room looking empty
([SableClient#685](SableClient#685) by @nushea)
* Fix read receipt scrolling not working
([SableClient#631](SableClient#631) by @Septicity)
* Fix status sometimes sticking in member tile
([SableClient#664](SableClient#664) by @nushea)
* Fix apng files not animating.
([SableClient#737](SableClient#737) by @7w1)
* Some fixes to sync requests being spammed on loading screen and for
multi-account background syncing, it should also load faster now!
([SableClient#736](SableClient#736) by @7w1)
* Fix other dmed party not being added as a founder by default when
creating a dm. ([SableClient#737](SableClient#737) by
@7w1)
* Update verbiage in the credits
([SableClient#728](SableClient#728) by @nushea)
* spoilered text now gets replaced with `[Spoiler]` in the plain text
fallback, as per MSC4454
([SableClient#715](SableClient#715) by @dozro)
* Hide copied settings links on dynamic rows
([SableClient#695](SableClient#695) by @hazre)
* Fix button hover background smearing in virtual list rows by
suppressing transform on hover
([SableClient#614](SableClient#614) by @Just-Insane)
* Fix Workbox precaching by removing injectionPoint override that was
silently disabling all precache entries
([SableClient#611](SableClient#611) by @Just-Insane)

### Change how settings links are shared
([SableClient#695](SableClient#695) by @hazre)

Settings links copied from Sable now stay on the current client URL and
include a small Sable marker in the link. That lets Sable recognize
settings links copied from other Sable instances without treating
unrelated third-party `/settings/...` links as Sable settings links.

When you send a bare settings link in the composer, Sable now rewrites
it into a labeled link so it looks better on non-Sable clients too. For
example: `[Settings > Account > Display
Name](https://client.example/settings/account?focus=display-name&moe.sable.client.action=settings)`.

Invalid or malformed settings-looking links now stay normal links
instead of being shown as settings chips.

If you previously set `settingsLinkBaseUrl` in `config.json`, remove it.
Sable now derives settings links from the runtime app URL, and the old
config key is no longer used.