docs: introduce versioned docs and migrate to fuma (#11166)

## Todos for release

- [x] Configure Env in docs project on vercel
- [x] Configure Root Path in the docs project on vercel
- [ ] Remove old CSP https://github.com/zitadel/website/pull/1592

## What we did

This pull request migrates the project documentation from the old
`docs/` directory to the new `apps/docs/` directory, introduces a new
documentation system built with Next.js and Fumadocs, and updates all
relevant references, configuration files, and documentation to reflect
this change. It also adds new configuration and ignore files for the new
documentation app, updates CI and linting to exclude the new docs from
certain checks, and revises the contributing guidelines accordingly.

**Documentation System Migration and New Docs App**

* Migrated all documentation from `docs/` to `apps/docs/`, and updated
all references in `README.md`, `CONTRIBUTING.md`, and other files to
point to the new location.
[[1]](diffhunk://#diff-eca12c0a30e25b4b46522ebf89465a03ba72a03f540796c979137931d8f92055L585-L640)
[[2]](diffhunk://#diff-eca12c0a30e25b4b46522ebf89465a03ba72a03f540796c979137931d8f92055L660-R607)
[[3]](diffhunk://#diff-eca12c0a30e25b4b46522ebf89465a03ba72a03f540796c979137931d8f92055L740-R687)
[[4]](diffhunk://#diff-b335630551682c19a781afebcf4d07bf978fb1f8ac04c6bf87428ed5106870f5L2-R3)
[[5]](diffhunk://#diff-b335630551682c19a781afebcf4d07bf978fb1f8ac04c6bf87428ed5106870f5L30-R30)
* Added a new Next.js/Fumadocs-based documentation app under
`apps/docs/`, including core app files, layouts, routing, search API,
and a comprehensive `README.md` with development and contribution
instructions.
[[1]](diffhunk://#diff-5a1b07344a2c1b4d3f37b23ff1388b62cd9f57dea3c1cd23d8a0412b7602b132R1-R74)
[[2]](diffhunk://#diff-462b9ad1eabbb7d1c29bb9c36e4931eb180fd7190900e6d2babf8f4d66ad1c28R1-R39)
[[3]](diffhunk://#diff-e16ae25660ded787b10ac35dea96d5ecaacf895dae0afc8a9bd4382dc79a8c87R1-R7)
[apps/docs/app/[[...slug]]/layout.tsxR1-R81](diffhunk://#diff-59e08acde4e805b7aeccef1dcf98f1d71dfc550777e6b9402085cee0e9fa4e0aR1-R81),
[apps/docs/app/[[...slug]]/page.tsxR1-R79](diffhunk://#diff-e5df3f80d0fa01e12d63d81f29c57a9d14e846c78fd3beabb2ef768e38fd9580R1-R79),
[[4]](diffhunk://#diff-389b34918e040cacaa87cd7201ffa462cc2b0b716736f537e3d3c660ac69353bR1-R7)
[[5]](diffhunk://#diff-d3b03416d1c457b19f1c27b26f2db741412df841b875c26ccadc36e4522247f4R1-R29)
[[6]](diffhunk://#diff-c8fb8339570a5305809be7c618e14705fd86390dc278e6ce8ba224a7bc8b0c3cR1-R25)

**Configuration and Tooling Updates**

* Updated `.github/workflows/codeql.yml`, `.golangci.yaml`, and
`.github/dependabot.yml` to properly handle the new docs app: excluded
`apps/docs` from certain checks, added npm dependency updates for the
docs app, and excluded generated content.
[[1]](diffhunk://#diff-12783128521e452af0cfac94b99b8d250413c516ec71fe6d97dbea666ff7ba27L8-R14)
[[2]](diffhunk://#diff-9917ddc9f1c3304218f7269265b746d997c5c0615478177b5fceecd33ef47cb5R5-R6)
[[3]](diffhunk://#diff-9917ddc9f1c3304218f7269265b746d997c5c0615478177b5fceecd33ef47cb5R126-R129)
[[4]](diffhunk://#diff-dd4fbda47e51f1e35defb9275a9cd9c212ecde0b870cba89ddaaae65c5f3cd28R89-R106)
* Updated `.devcontainer/devcontainer.json` to use the latest Go 1.25.3
version for consistency.

**Licensing and Miscellaneous**

* Added `apps/docs/` to the list of licensed directories in
`LICENSING.md`.

These changes ensure the documentation is now maintained in a modern,
scalable system and all project tooling is updated to support the new
structure.

---------

Co-authored-by: Federico Coppede <[email protected]>

apps/docs/content/self-hosting/manage/reverseproxy/zitadel_cloud/index.mdx

@@ -0,0 +1,16 @@
+---
+title: Front Zitadel Cloud with a CDN, WAF or Reverse Proxy
+sidebar_label: Fronting Zitadel Cloud
+---
+
+## Fronting Zitadel Cloud
+
+You can use your reverseproxy, content delivery network (CDN) or web application firewall (WAF) to front Zitadel Cloud.
+However we currently do not recommend this for production settings.
+
+To configure your service that fronts Zitadel please have a look at the vendors in this page.
+
+## Things to look out for when fronting Zitadel Cloud
+
+- Cache-control - Zitadel Cloud uses a CDN to globally distribute data. Please try to avoid overriding this header as it may lead to sideeffects
+- Rate Limits - Zitadel Cloud uses a combination of static and dynamic rate limits. If you receive occasional 429 headers you are rate limited.