binarybeachio: account chooser, brand logo, session convention

Three small fork tweaks bundled together; none touch upload flow:

* OIDC: pass `prompt=select_account` so Zitadel always shows its account
  picker rather than silently passing through an existing session. Override
  with OIDC_PROMPT env var.
* Branding: swap "with binarybeach.io" -> "with BinaryBeach.io" and replace
  GitHub light/dark logo imports with our brand mark (works on both themes).
* Session: thread the binarybeachio session-lifecycle convention values
  (SESSION_COOKIE_AGE, ADMIN_SESSION_COOKIE_AGE, SESSION_SAVE_EVERY_REQUEST)
  through docker-compose.bb-local.yml app-env mixin and document the
  cross-fork convention link in BINARYBEACHIO.md.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/core/hooks/oauth/core.tsx

@@ -11,8 +11,9 @@ import { API_BASE_URL } from "@plane/constants";
 import type { TOAuthConfigs, TOAuthOption } from "@plane/types";
 // assets
 import giteaLogo from "@/app/assets/logos/gitea-logo.svg?url";
-import GithubLightLogo from "@/app/assets/logos/github-black.png?url";
-import GithubDarkLogo from "@/app/assets/logos/github-dark.svg?url";
+// binarybeachio fork: swapped GitHub logo imports for our brand logo. Same
+// asset for light and dark theme (the orange/teal palette reads on both).
+import BinarybeachLogo from "@/app/assets/logos/binarybeach-logo.png?url";
 import gitlabLogo from "@/app/assets/logos/gitlab-logo.svg?url";
 import googleLogo from "@/app/assets/logos/google-logo.svg?url";
 // hooks
@@ -51,15 +52,8 @@ export const useCoreOAuthConfig = (oauthActionText: string): TOAuthConfigs => {
       // Zitadel — see provider/oauth/github.py). Branding is rebranded here;
       // backend identifiers (route, env vars, DB provider key) stay "github".
       id: "github",
-      text: `${oauthActionText} with binarybeach.io`,
-      icon: (
-        <img
-          src={resolvedTheme === "dark" ? GithubDarkLogo : GithubLightLogo}
-          height={18}
-          width={18}
-          alt="binarybeach.io SSO"
-        />
-      ),
+      text: `${oauthActionText} with BinaryBeach.io`,
+      icon: <img src={BinarybeachLogo} height={18} width={18} alt="Binary Beach" />,
       onClick: () => {
         window.location.assign(`${API_BASE_URL}/auth/github/${next_path ? `?next_path=${next_path}` : ``}`);
       },