refactor(level): four essential rungs only — integration & recipe-local are optional

Per operator: the level ladder is now the FOUR essential rungs every recipe is
held to — install, upgrade (essential), backup/restore, functional (top = L4).
Integration (SSO/OIDC) and recipe-local are OPTIONAL capabilities: they no longer
appear as level rungs or skip rows and never cap the level. SSO is still enforced
for the run VERDICT (unchanged in run_recipe_ci.py); it just doesn't affect the
level. derive_rungs simplified accordingly (drops declared/deps/sso/repo-local
inputs). custom-html-tiny's EXPECTED_NA is back to just backup_restore.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

runner/harness/card.py

@@ -141,14 +141,12 @@ def _stage_rows(stages: list[dict]) -> str:
     return "\n".join(rows) or '<tr><td colspan="3">no stages</td></tr>'
 
 
-# Friendly rung labels for the skip rows.
+# Friendly rung labels for the skip rows (the four essential rungs).
 RUNG_LABEL = {
     "install": "install",
     "upgrade": "upgrade",
     "backup_restore": "backup/restore",
     "functional": "functional",
-    "integration": "integration",
-    "recipe_local": "recipe-local",
 }
 SKIP_GREEN = "#57ab5a"  # muted green — an intentional skip reads like a pass (but labelled, never inflating)
 
@@ -241,7 +239,7 @@ tr.skipreason td{{color:#8b949e;font-size:.78rem;font-style:italic;padding-top:0
 <div class="hd">{FLOWER_SVG}
 <div class="title"><h1>{recipe}</h1><span class="ver">{version}</span></div>
 <div class="lvl"><span class="num">{level}</span><span class="lbl">level</span></div></div>
-<div class="cap">{("<b>capped:</b> " + cap) if cap else "<b>full clean climb</b> — top level (6)"}</div>
+<div class="cap">{("<b>capped:</b> " + cap) if cap else "<b>full clean climb</b> — top level (4)"}</div>
 <div class="body"><div class="tbl"><table>{rows}</table></div>{shot_html}</div>
 <div class="flags">{"".join(flag_bits)}</div>
 </div></body></html>"""