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/cjs-sdk-bridge-integration.test.cjs

@@ -4,7 +4,7 @@
  * Integration test for `get-shit-done/bin/lib/cjs-sdk-bridge.cjs` — locks the
  * load-success invariant that Phase 5/6 silently violated before this PR.
  *
- * Original bug: the bridge used `require('@gsd-build/sdk')` to load the
+ * Original bug: the bridge used `require('@gsd-redux/sdk')` to load the
  * runtime-bridge module. That package name is not resolvable from the root
  * `node_modules` (the SDK lives at `./sdk/` as a sibling, not a dependency),
  * and even if it were, the public entry didn't expose `executeForCjs` or