feat: live charge limit, identity retunes, btop assets (product calls)

- Charge limit: udev GROUP=users on threshold; menu applies sysfs live
  and persists state; boot/AC oneshot prefers live theme-state.json.
- Look & Feel: Reset wallpaper (auto); Theme/next/night light already there.
- NVIDIA first-class wrappers deferred past v1 (keep #59 comments).
- Identity taste: white, lumon, hackerman, matte-black, miasma.
- Hand btop.theme for identity + boreal/executive-slate/neon-glass.

Verified: V0 contrast; V1 battery-charge-limit VM. V3 live sysfs on laptop.

themes/boreal/btop.theme

@@ -0,0 +1,25 @@
+theme[main_bg]="#21272F"
+theme[main_fg]="#D3DAE0"
+theme[title]="#D3DAE0"
+theme[hi_fg]="#B79BE8"
+theme[selected_bg]="#404D5C"
+theme[selected_fg]="#D3DAE0"
+theme[inactive_fg]="#5E6A78"
+theme[graph_text]="#97A3B2"
+theme[meter_bg]="#303A46"
+theme[proc_misc]="#86C7C0"
+theme[cpu_box]="#B79BE8"
+theme[mem_box]="#A3CF88"
+theme[net_box]="#86C7C0"
+theme[proc_box]="#303A46"
+theme[div_line]="#404D5C"
+theme[temp_start]="#A3CF88"
+theme[temp_mid]="#E6C384"
+theme[temp_end]="#E2818A"
+theme[cpu_start]="#A3CF88"
+theme[cpu_mid]="#E6C384"
+theme[cpu_end]="#E2818A"
+theme[free_start]="#A3CF88"
+theme[used_start]="#E6C384"
+theme[download_start]="#B79BE8"
+theme[upload_start]="#86C7C0"