Codex is per-project, not machine-wide

The installer cannot run `--runtime codex` for you: the verb requires a
project, since one of its targets is the project's own AGENTS.md. It now
detects codex and prints the command to run in each project instead.

Signed-off-by: disqualifier <dev@disqualifier.me>

install.ps1

@@ -243,15 +243,6 @@ if (-not $serviceOnly) {
   & standup install --runtime claude
   if ($LASTEXITCODE -ne 0) { Warn 'runtime install reported a problem; see doctor below' }
 
-  # Codex only where its binary exists: `--runtime codex` writes to
-  # $CODEX_HOME/hooks.json, ~/.agents/skills/ and the project's AGENTS.md, and
-  # leaving marked blocks for a tool that is not installed is worse than
-  # skipping. -NoCodex opts out on a box that does have it.
-  if (-not $NoCodex -and $codexBin) {
-    & standup install --runtime codex
-    if ($LASTEXITCODE -ne 0) { Warn 'codex runtime install reported a problem; see doctor below' }
-  }
-
   if ($probe -and -not $probe.HasExited) { Stop-Process -Id $probe.Id -Force -ErrorAction SilentlyContinue }
   Remove-Item -Recurse -Force $probeDir -ErrorAction SilentlyContinue
 }
@@ -309,4 +300,13 @@ Write-Host ''
 & standup code
 Write-Host ''
 Write-Host 'Next: cd <your project>; standup create'
+# Codex's runtime is per-project -- one of its three targets is the project's
+# own AGENTS.md -- so the installer cannot wire it from here: there is no
+# project yet, and the runtime step's throwaway is deleted. Name the command
+# instead, only where codex exists and the user has not opted out.
+if (-not $NoCodex -and $codexBin) {
+  Write-Host ''
+  Write-Host 'Codex is installed here. In each project you want it in:'
+  Write-Host '  standup install --runtime codex    # hooks, skill, a block in AGENTS.md'
+}
 }