cwc-makers: curl+tar fallback when git is missing

/maker-setup now falls back to GitHub's tarball endpoint when git isn't
on PATH, instead of detouring through a package-manager git install.
curl and tar ship with macOS, Linux, and Windows 10 1803+ out of the
box, so this is zero-install on every target platform — and a CwC
attendee just needs the files once to flash a device, not git history.

- maker-setup.md: git-clone fast path, curl|tar (Unix) / curl+tar+
  Rename-Item (PowerShell) fallback, normalizes the -main suffix
- m5-onboard/SKILL.md: drop git from required deps + per-OS git
  bootstrap block; keep Python bootstrap
- README: git now listed as optional

Linear: CC-1975

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

🏠 Remote-Dev: homespace

.claude-plugin/marketplace.json

@@ -904,6 +904,16 @@
       "source": "./external_plugins/gitlab",
       "homepage": "https://github.com/anthropics/claude-plugins-public/tree/main/external_plugins/gitlab"
     },
+    {
+      "name": "goodmem",
+      "description": "GoodMem memory infrastructure for AI agents. Use Python SDK skills to write code that manages embedders, spaces, and memories, or use MCP tools to perform GoodMem operations directly via natural language.",
+      "source": {
+        "source": "url",
+        "url": "https://github.com/PAIR-Systems-Inc/goodmem-claude-code-plugin.git",
+        "sha": "4e23ab2b3bc7cb4167c99e10d9640ad7089744d7"
+      },
+      "homepage": "https://github.com/PAIR-Systems-Inc/goodmem-claude-code-plugin"
+    },
     {
       "name": "gopls-lsp",
       "description": "Go language server for code intelligence and refactoring",