feat: Add Compression to Hacker News w/ Islands Example

[Th3Whit3Wolf]

One of the things I love about leptos is how easy it is to ship a small frontend.

Leptos provides islands that reduce the amount of total HTML generated and it's build tool minifies CSS with lightningcss, soon will be minifying javascript with swc, and it can even precompress these static assets. That last of which I think may be the most important because web assembly compress fairly well and it allows the user to ship their entire app as 1 static binary (with musl).

Since precompression was added as a feature in cargo-leptos I haven't seen it mentioned a whole lot so I wanted to help people see how to use it. I have also seen a couple question about setting up compression in general so I added that too.

I've updated the hackernews_islands_axum example to serve all static assets precompressed with cargo-leptos and to dynamically compress the HTML.

The type of compression sent will depend on what the client supports.

The resulting network usage

Asset	No Compression	Compression	Difference
HTML	16.25 kB	4.80 kB	- 70.46%
CSS	3.84 kB	1.17 kB	- 69.53%
JS	16.86 kB	4.63 kB	- 72.53%
WASM	200.15 kB	69.93 kB	- 65.06%
ICON	15.54 kB	3.29 kB	- 78.83%
TOTAL	252.64 kB	83.82 kB	- 66.82%

[Th3Whit3Wolf]

Fix lints for CI

[Th3Whit3Wolf]

Looks like the issue is that when building it is trying to access target/site which doesn't exist until cargo leptos build is run. I have updated the makefile to account for this.

[Th3Whit3Wolf]

I also add hash_file to the Cargo.toml. Since the compressed file are served with a Cache-Control policy hash_file is necessary to ensure that client receives the correct file when updates are made to an asset. I don't expect the example files to change much but for users copying & pasting this example to base their own app off of this will be helpful.

[gbj]

Cool -- This looks great, thanks!