chore: rebrand to GSD-redux/get-shit-done-redux

Mirror of code, issues, and PRs from the upstream gsd-build/get-shit-done,
which appears compromised or abandoned (maintainer unreachable since
2026-04-01; $GSD token linked to rug-pull).

- Adds rebrand notice block at top of English README
- Removes $GSD token badge and @gsd_foundation X badge (keeps Discord)
- Renames npm packages: get-shit-done-cc -> get-shit-done-redux,
  @gsd-build/sdk -> @gsd-redux/sdk
- Updates all repo URLs across docs, workflows, package.json, bin/
- Updates ci@gsd-build -> ci@gsd-redux in workflow git identities
- Leaves CHANGELOG and .changeset/* alone (historical, time-stamped)

tests/bug-2829-local-install-sdk-path.test.cjs

@@ -1,7 +1,7 @@
 /**
  * Regression test for #2829: `command not found: gsd-sdk` with local-mode install.
  *
- * Repro: a fresh `npx get-shit-done-cc@latest` install with the runtime set
+ * Repro: a fresh `npx get-shit-done-redux@latest` install with the runtime set
  * to local mode left every `gsd-sdk query …` call site unable to resolve the
  * binary because the installer's previous behavior was to skip SDK linking
  * entirely for local installs (#2678 over-corrected). The published tarball