docs(copilot): say plainly that the lifecycle slash commands never appear in Copilot

#542 reports following docs/copilot-setup.md and finding no /spec, /plan,
/build or /test. The doc already says the wrappers are Claude Code
commands, but in the middle of a paragraph that a reader scanning for
install steps walks past; the reporter did. The maintainer's answer on
the issue was that the doc should make this explicit.

Add a callout right after the intro that names the commands, says they
are expected to be absent, and points to the skill-name mapping and the
optional aliases. Add a lead-in to the troubleshooting list that rules
out the expected case before the real diagnostics. Add one sentence to
the README's Copilot entry so the expectation is set before the doc is
opened.

Closes #542

docs/copilot-setup.md

@@ -4,6 +4,8 @@ This guide covers Copilot in VS Code. For the standalone `copilot` command-line
 
 **What an install actually gives you:** the skills. Each installed skill becomes a slash command named after its frontmatter `name` — `/spec-driven-development`, `/test-driven-development`, and so on. `npx skills add addyosmani/agent-skills` and the manual copy below both install skills only. Neither of those two routes copies this repo's short lifecycle wrappers (`/spec`, `/plan`, `/build`, `/test`, `/review`, `/ship`) — those are Claude Code commands living in `.claude/commands/`. Use the full skill names, or add your own aliases — see [Lifecycle workflows](#lifecycle-workflows).
 
+> **`/spec`, `/plan`, `/build`, `/test`, `/review`, `/code-simplify`, `/webperf` and `/ship` never appear in Copilot.** They are Claude Code commands, and Copilot does not read `.claude/commands/`. Not seeing them after an install is expected, not a missing step. Invoke the skill by its own name instead — `/spec-driven-development` for `/spec`, `/planning-and-task-breakdown` for `/plan`, and so on; the full mapping is in [Lifecycle Workflows](#lifecycle-workflows). On VS Code you can add [short aliases](#optional-short-spec-style-aliases) yourself if you want the short forms.
+
 ## Setup
 
 ### Copilot Instructions
@@ -145,6 +147,8 @@ Write the body yourself, or take it from this table, rather than copying `.claud
 
 ### If the skill slash commands don't appear
 
+First rule out the expected case: if the only commands you miss are the short lifecycle wrappers (`/spec`, `/plan`, `/build`, `/test`, `/review`, `/ship`), nothing is wrong — those are Claude Code commands and never surface in Copilot (see the note at the top). The steps below are for when the skills' own names, such as `/spec-driven-development`, are missing too.
+
 Work through these in order — `/spec-driven-development` missing and `/spec` missing have different causes:
 
 1. **Check where the skills landed.** Each one needs its own directory containing a `SKILL.md`. The project-level paths this guide uses are `.github/skills/`, `.claude/skills/` and `.agents/skills/` — but an installer run with a global/user flag writes outside the workspace instead (`~/.agents/skills/` and equivalents), so a skill that isn't in any of the three may simply be installed personally. Confirm the actual path against the [VS Code agent skills docs](https://code.visualstudio.com/docs/agent-customization/agent-skills), then re-install into the project if you wanted it project-scoped.