fix(auth): isolate session cookies from other Auth.js apps on same host (#5996)

Prefix all Auth.js cookies (default "homarr") so they no longer collide
with other Auth.js apps on the same hostname.

apps/docs/docs/advanced/single-sign-on/index.mdx

@@ -23,6 +23,7 @@ Homarr supports multiple authentication options, from internal userbase (credent
 | AUTH_PROVIDERS             | Select Which provider to use between *credentials*, *ldap* and *oidc*. <br /> Multiple providers can be enabled with by separating them with `,`, (ex. `AUTH_PROVIDERS=credentials,oidc`, it is highly recommended to just enable one provider).  |  credentials  |
 | AUTH_LOGOUT_REDIRECT_URL  | URL to redirect to after clicking logging out.  | --- |
 | AUTH_SESSION_EXPIRY_TIME  | Time for the session to time out. Can be set as pure number, which will automatically be used in seconds, or followed by s, m, h or d for seconds, minutes, hours or days. (ex: "30m") | "30d"  |
+| AUTH_COOKIE_PREFIX  | Prefix used for all authentication cookies (session, csrf, callback, pkce, state, nonce). Change this if you run another Auth.js/NextAuth app on the same hostname as Homarr (browsers scope cookies by host, not by port) to avoid cookie name collisions. Only letters, numbers, hyphens and underscores are allowed. | `homarr`  |
 
 <Tabs>
   <TabItem value="credentials" label="Credentials Provider" default>

apps/docs/docs/getting-started/installation/helm.md

@@ -395,6 +395,7 @@ All available values are listed on the [artifacthub](https://artifacthub.io/pack
 | env.AUTH_LDAP_USERNAME_FILTER_EXTRA_ARG | string | `nil` | Extra arguments for user search filter (& based) |
 | env.AUTH_LDAP_USER_MAIL_ATTRIBUTE | string | `"mail"` | Attribute used for mail field |
 | env.AUTH_LOGOUT_REDIRECT_URL | string | `nil` | URL to redirect to after clicking logging out. |
+| env.AUTH_COOKIE_PREFIX | string | `"homarr"` | Prefix used for all authentication cookies. Change if you run another Auth.js/NextAuth app on the same hostname to avoid cookie name collisions. Only letters, numbers, hyphens and underscores. |
 | env.AUTH_OIDC_AUTO_LOGIN | string | `"false"` | Automatically redirect to OIDC login |
 | env.AUTH_OIDC_CLIENT_NAME | string | `"OIDC"` | Display name of provider (in login screen) |
 | env.AUTH_OIDC_GROUPS_ATTRIBUTE | string | `"groups"` | Attribute used for groups (roles) claim |