all: do not commit generated JS/CSS to source control (#148)

Closes #125
Closes #40

Among other things, this moves all of the asset generation to run within
the context of an npm script. Developer documentation stubs have been
added so that people can get started more easily.

The top-level Dockerfile (which is no longer used in production) has
been removed as its presence has been causing confusion. This changeset
will break it anyways.

These changes will make for less "repo churn" as the static assets are
built and rebuilt, at the cost of making the build step more complicated
for downstream packagers. If this becomes a burden, we can explore
making a "release tarball" that contains pre-massaged outputs.

docs/docs/developer/local-dev.md

@@ -0,0 +1,57 @@
+---
+title: Local development
+---
+
+:::note
+
+TL;DR: `npm ci && npm run dev`
+
+:::
+
+Anubis requires the following tools to be installed to do local development:
+
+- [Go](https://go.dev) - the programming language that Anubis is written in
+- [esbuild](https://esbuild.github.io/) - the JavaScript bundler Anubis uses for its production JS assets
+- [Node.JS & NPM](https://nodejs.org/en) - manages some build dependencies
+- `gzip` - compresses production JS (part of coreutils)
+- `zstd` - compresses production JS
+- `brotli` - compresses production JS
+
+If you have [Homebrew](https://brew.sh) installed, you can install all the dependencies with one command:
+
+```text
+brew bundle
+```
+
+If you don't, you may need to figure out equivalents to the packages in Homebrew.
+
+## Running Anubis locally
+
+```text
+npm run dev
+```
+
+Or to do it manually:
+
+- Run `npm run assets` every time you change the CSS/JavaScript
+- `go run ./cmd/anubis` with any CLI flags you want
+
+## Building JS/CSS assets
+
+```text
+npm run assets
+```
+
+If you change the build process, make sure to update `build.sh` accordingly.
+
+## Production-ready builds
+
+```text
+npm run container
+```
+
+This builds a prod-ready container image with [ko](https://ko.build). If you want to change where the container image is pushed, you need to use environment variables:
+
+```text
+DOCKER_REPO=registry.host/org/repo DOCKER_METADATA_OUTPUT_TAGS=registry.host/org/repo:latest npm run container
+```