docs: normalize code-fence languages for Shiki compatibility (#27161)

Normalizes non-standard code-fence language tags across `docs/**` so a
strict highlighter (Shiki, used by Fumadocs) won't fail the build on an
unrecognized language, and unifies redundant synonym tags onto one
canonical form per language. The current renderer (Speed-Highlight)
detects the language from the code content, not the fence label, so this
drift wasn't visible until now.

## Changes

- `hcl` -> `tf` (199 fences, including indented ones nested in
numbered/bulleted lists). Shiki ships `hcl` and `terraform` as two
distinct grammars (not aliases); every `hcl`-tagged fence in `docs/**`
is actually Terraform resource/data/provider syntax, so the more
specific `terraform` grammar is correct for all of them. `tf` is Shiki's
own alias for that grammar, and it's also what GitHub's own markdown
renderer resolves to the same HCL/Terraform highlighting.
- `pwsh`/`powershell` -> `ps1`. Both `ps` and `ps1` are registered
PowerShell aliases in Shiki, but on GitHub's renderer only `.ps1` is a
registered file extension (`.ps` isn't), so `ps1` renders identically to
`powershell` there today while bare `ps` would silently lose
highlighting.
- `env` -> `dotenv` (a dedicated Shiki grammar for `KEY=VALUE` files)
- `text`/`output`/`none`/`url` -> `txt`. Same built-in plain-text
fallback either way, just shorter.
- `Dockerfile` -> `dockerfile` (lowercase)
- `bash`/`shell` -> `sh` (732 fences). Shiki and GitHub both alias all
three to a single shell grammar; this was already the style guide's
stated preference, just not enforced across the existing corpus until
now.
- `markdown` -> `md` (4 fences). Alias of the same grammar in both Shiki
and GitHub.
- `jsonc` -> `json` (1 fence). The block has no comments or trailing
commas, so it doesn't need the comments-capable grammar.
- `ts` -> `tsx` (2 fences, `docs/about/contributing/frontend.md`).
Verified the actual content tokenizes identically under both grammars,
and a sibling block in the same file already needs `tsx` for real JSX,
so unifying to one tag is safe for this file. Documented a caveat: `tsx`
mis-tokenizes the legacy angle-bracket type-assertion syntax
(`<Type>value`), which is invalid in real `.tsx` files anyway, so use
`value as Type` instead.
- `yml` -> `yaml` (1 fence)
- Updated `docs/.style/style-guide/formatting.md` to document all
canonical tags

`promql` (2 fences) and `caddyfile` (2 fences) are left as-is. Shiki
doesn't bundle a grammar for either, so they need a custom grammar
registration when the site adopts Shiki, rather than degrading to `txt`.
Tracked as follow-up work under DOCS-118 and
[DOCS-544](https://linear.app/codercom/issue/DOCS-544/vendor-a-local-promql-grammar-for-shiki-syntax-highlighting)
(promql).

Does not touch `offlinedocs/`.

Linear:
[DOCS-476](https://linear.app/codercom/issue/DOCS-476/normalize-docs-code-fence-languages-de-risk-shikifumadocs)

<details>
<summary>How the fence tags were verified</summary>

Each tag was tested against a real `shiki@latest` highlighter instance
(`codeToHtml`/`codeToTokens`) and cross-checked against GitHub's
`@wooorm/starry-night` grammar sources (the renderer that actually
displays these `.md` files today, in repo browsing and PR diffs), since
that's what determines whether brevity is safe before Shiki adoption:

```text
FAIL  env        -- Language `env` is not included in this bundle.
FAIL  Dockerfile -- Language `Dockerfile` is not included in this bundle.
FAIL  promql     -- Language `promql` is not included in this bundle.
FAIL  caddyfile  -- Language `caddyfile` is not included in this bundle.
FAIL  pwsh       -- Language `pwsh` is not included in this bundle.
FAIL  output     -- Language `output` is not included in this bundle.
```

`hcl` doesn't error in Shiki, since it's a real grammar, but that's
exactly the trap: it was silently rendering every fence with the generic
HCL grammar instead of the Terraform-specific one. Every `hcl`-tagged
fence in `docs/**` was manually checked against `origin/main` and is
genuinely Terraform content.

For `ts`/`tsx`, tokenizing the actual doc content confirmed identical
output under both grammars; a synthetic test with the legacy
angle-bracket cast syntax confirmed `tsx` degrades on that specific
construct, which the style guide now calls out.

The first normalization pass only matched fence tags at column 0
(`^```tag$`), missing tags indented inside numbered/bulleted lists. A
follow-up pass caught the remaining occurrences at any indentation
level.

</details>


---

*This PR description and the underlying changes were prepared with Coder
Agents assistance.*

docs/tutorials/reverse-proxy-apache.md

@@ -5,7 +5,7 @@
 1. Start a Coder deployment and be sure to set the following
    [configuration values](../admin/setup/index.md):
 
-   ```env
+   ```dotenv
    CODER_HTTP_ADDRESS=127.0.0.1:3000
    CODER_ACCESS_URL=https://coder.example.com
    CODER_WILDCARD_ACCESS_URL=*coder.example.com
@@ -24,13 +24,13 @@
 
 3. Install Apache (assuming you're on Debian/Ubuntu):
 
-   ```shell
+   ```sh
    sudo apt install apache2
    ```
 
 4. Enable the following Apache modules:
 
-   ```shell
+   ```sh
    sudo a2enmod proxy
    sudo a2enmod proxy_http
    sudo a2enmod ssl
@@ -39,7 +39,7 @@
 
 5. Stop Apache service and disable default site:
 
-   ```shell
+   ```sh
    sudo a2dissite 000-default.conf
    sudo systemctl stop apache2
    ```
@@ -70,7 +70,7 @@ providers, refer to the
    dns_cloudflare_api_token = YOUR_API_TOKEN
    ```
 
-   ```shell
+   ```sh
    mkdir -p ~/.secrets/certbot
    touch ~/.secrets/certbot/cloudflare.ini
    nano ~/.secrets/certbot/cloudflare.ini
@@ -78,7 +78,7 @@ providers, refer to the
 
 3. Set the correct permissions:
 
-   ```shell
+   ```sh
    sudo chmod 600 ~/.secrets/certbot/cloudflare.ini
    ```
 
@@ -86,7 +86,7 @@ providers, refer to the
 
 1. Create the wildcard certificate:
 
-   ```shell
+   ```sh
    sudo certbot certonly --dns-cloudflare --dns-cloudflare-credentials ~/.secrets/certbot/cloudflare.ini -d coder.example.com -d *.coder.example.com
    ```
 
@@ -97,7 +97,7 @@ you're using `coder.example.com` as your subdomain.
 
 1. Create Apache configuration for Coder:
 
-   ```shell
+   ```sh
    sudo nano /etc/apache2/sites-available/coder.conf
    ```
 
@@ -137,13 +137,13 @@ you're using `coder.example.com` as your subdomain.
 
 3. Enable the site:
 
-   ```shell
+   ```sh
    sudo a2ensite coder.conf
    ```
 
 4. Restart Apache:
 
-   ```shell
+   ```sh
    sudo systemctl restart apache2
    ```
 
@@ -151,19 +151,19 @@ you're using `coder.example.com` as your subdomain.
 
 1. Create a new file in `/etc/cron.weekly`:
 
-   ```shell
+   ```sh
    sudo touch /etc/cron.weekly/certbot
    ```
 
 2. Make it executable:
 
-   ```shell
+   ```sh
    sudo chmod +x /etc/cron.weekly/certbot
    ```
 
 3. And add this code:
 
-   ```shell
+   ```sh
    #!/bin/sh
    sudo certbot renew -q
    ```