feat: overhaul entire documentation (#10)

### Explanation

_No response_

### Issue

_No response_

### Attestations

- [x] I have read and agree to the [Code of Conduct](https://docs.nhcarrigan.com/community/coc/)
- [x] I have read and agree to the [Community Guidelines](https://docs.nhcarrigan.com/community/guide/).
- [x] My contribution complies with the [Contributor Covenant](https://docs.nhcarrigan.com/dev/covenant/).

### Dependencies

- [x] I have pinned the dependencies to a specific patch version.

### Style

- [x] I have run the linter and resolved any errors.
- [x] My pull request uses an appropriate title, matching the conventional commit standards.
- [x] My scope of feat/fix/chore/etc. correctly matches the nature of changes in my pull request.

### Tests

- [ ] My contribution adds new code, and I have added tests to cover it.
- [ ] My contribution modifies existing code, and I have updated the tests to reflect these changes.
- [ ] All new and existing tests pass locally with my changes.
- [ ] Code coverage remains at or above the configured threshold.

### Documentation

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### Versioning

Major - My pull request introduces a breaking change.

Reviewed-on: #10
Co-authored-by: Naomi Carrigan <commits@nhcarrigan.com>
Co-committed-by: Naomi Carrigan <commits@nhcarrigan.com>

astro.config.mjs

@@ -3,6 +3,7 @@ import starlight from "@astrojs/starlight";
 import { ExpressiveCodeTheme } from "@astrojs/starlight/expressive-code";
 import themeJson from "./src/styles/theme.json";
 import darkThemeJson from "./src/styles/theme-dark.json";
+import mermaid from "astro-mermaid";
 
 import { navigation } from "./src/components/navigation.ts";
 
@@ -16,6 +17,7 @@ const sakuraDreamsDark = ExpressiveCodeTheme.fromJSONString(
 export default defineConfig({
   site: "https://docs.nhcarrigan.com",
   integrations: [
+    mermaid(),
     starlight({
       components: {
         Footer: "./src/components/Footer.astro",