feat: print a glyph self-test at the end of install

An installer can guarantee the assets and the font are in place but not that
the terminal actually draws the glyphs - that is the one thing decided on the
target machine at display time. Emitting the exact symbol set lets the user
confirm rendering at a glance and points a failing case at the terminal choice
rather than a missing font, which is the only remaining variable.

install.ps1

@@ -169,10 +169,18 @@ if ($SkipFont) {
     Install-NerdFont -FontName $FontName
 }
 
+# --- Glyph self-test --------------------------------------------------------
+# The only thing this script cannot check is whether the terminal actually
+# draws the glyphs. Print the exact symbol set so the user can eyeball it: if
+# any show as boxes/question marks, the terminal (not the font) is the problem.
+Write-Host "`nGlyph self-test - these should all be real symbols, not boxes:" -ForegroundColor White
+Write-Host "  🤖  ⚡  🧠  🔢  ⏰  ⏳  📅  █  ░" -ForegroundColor Cyan
+Write-Host "  If any appear as boxes/? , switch to Windows Terminal (Win11 default)."
+
 # --- Post-install notes -----------------------------------------------------
 Write-Host "`nDone." -ForegroundColor Green
 Write-Host "Notes:" -ForegroundColor White
-Write-Host "  ->  The statusline itself needs no special font - its icons are standard Unicode"
-Write-Host "      (emoji + block chars) that render via the OS emoji fallback. The Nerd Font above"
-Write-Host "      is an optional safety net for the widest glyph coverage."
+Write-Host "  ->  Symbols are standard Unicode (emoji + block chars). Windows Terminal renders"
+Write-Host "      them via Segoe UI Emoji by default - no special font needed. The Nerd Font"
+Write-Host "      above is an optional safety net."
 Write-Host "  Restart Claude Code (or start a new session) to see the statusline.`n"