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/cline-install.test.cjs

@@ -7,7 +7,7 @@
  * Regression tests for bug #1991
  *
  * Cline is listed in GSD documentation as a supported runtime but was
- * completely absent from bin/install.js. Running `npx get-shit-done-cc`
+ * completely absent from bin/install.js. Running `npx get-shit-done-redux`
  * did not show Cline as an option in the interactive menu.
  *
  * Fixed: Cline is now a first-class runtime that: