Phase C: alphabetize README platform listings + spec

Quickstart link list and the per-harness install sub-sections both
reorder to strict alphabetical:

  Claude Code, Codex App, Codex CLI, Cursor, Factory Droid,
  Gemini CLI, GitHub Copilot CLI, OpenCode

Three blocks moved (Codex App swaps with Codex CLI; Cursor moves up
two slots; GitHub Copilot CLI moves up one). Claude Code stays first
by alphabetical chance.

Each install sub-section's content is byte-identical pre/post —
only the positions change. Quickstart anchors verified against the
new heading order.

docs/superpowers/specs/2026-05-05-platform-neutral-readme-design.md

@@ -0,0 +1,47 @@
+# Platform-neutral README ordering — Phase C design
+
+## Background
+
+Phases A and B (see `2026-05-05-platform-neutral-prose-design.md` and `2026-05-05-platform-neutral-config-refs-design.md`) already neutralized generic Claude prose and config-file references in the README. The remaining platform-leaning signal is layout: the README's two platform listings put Claude Code first and aren't strictly alphabetical elsewhere.
+
+This phase fixes the ordering. No prose changes.
+
+## In scope
+
+1. **Quickstart platform list** (`README.md:7`) — the inline link list of supported harnesses
+2. **Installation section ordering** (`README.md:35–152`) — the per-harness install sub-sections
+
+## Out of scope
+
+- Prose, marketplace names, plugin IDs, URLs — all factually correct as-is.
+- Visual weight of the Claude Code section (which has two sub-sections — official Anthropic marketplace and Superpowers marketplace). Both are real install paths; collapsing them would hide accurate info.
+- Section headings and content within each install block — only the ordering of the blocks changes.
+
+## Substitution
+
+Both listings reorder to strict alphabetical:
+
+| Old order | New order |
+|-----------|-----------|
+| Claude Code | Claude Code |
+| Codex CLI | Codex App |
+| Codex App | Codex CLI |
+| Factory Droid | Cursor |
+| Gemini CLI | Factory Droid |
+| OpenCode | Gemini CLI |
+| Cursor | GitHub Copilot CLI |
+| GitHub Copilot CLI | OpenCode |
+
+Three moves: Codex App swaps with Codex CLI; Cursor moves up two slots; GitHub Copilot CLI moves up one.
+
+Claude Code remains first by alphabetical chance (`Cl…` precedes `Co…`).
+
+## Commit plan
+
+One atomic commit covering both listings, since changing one without the other would create inconsistency between the quickstart and the installation section.
+
+## Verification
+
+- Quickstart anchors (`#claude-code`, `#codex-app`, etc.) still resolve to existing `### …` headings — no headings renamed.
+- Each install sub-section's body is byte-identical pre/post; only positions changed.
+- `git diff README.md` shows section moves only, no content edits.