fix(tools): identity audit exemptions + import hierarchy (#69 #70)

#69: audit-theme-design tags hue/CVD/ANSI-family noise on white,
vantablack, lumon, hackerman, matte-black, miasma as [identity] with a
legend — do not retune identity palettes into traffic lights.

#70: import-palettes keeps surface≠overlay when color0==color8, derives
light UI chips from base (ANSI-black trap), gentler light mantle; roles
are first-class. No bulk re-import of shipped theme JSON.

Verified: V0 (py_compile + synthetic import fixtures + audit report).

README.md

@@ -446,7 +446,10 @@ reload                          # exec zsh (reload the shell)
 - **New themed value:** add the key to `theme-state.json` and consume it in
   the Nix modules. One place — there is no second renderer to keep in sync.
 - **Importing more old-distro palettes:**
-  `tools/import-palettes.py <palettes-dir> themes/`.
+  `tools/import-palettes.py <palettes-dir> themes/` (roles are first-class:
+  when ANSI color0==color8 the tool derives an overlay step; light themes
+  do not use dark ANSI black as surface — hand-tune after import; do not
+  bulk-reimport shipped JSON without a hierarchy pass).
 - **New opt-in feature (convention):** when a feature is off by default and
   needs the user to set `nomarchy.*` options (e.g. night light, per-device
   keyboard layouts, monitor layout, power management), ship a **commented**