Session overhaul: dev tooling, cleanup, theming, fixes

Tooling:
- nh + nvd/nom/statix/deadnix/comma (new programs/nix.nix); GC via nh clean
- zoxide (cd), atuin, just, lazydocker, dust, duf, difftastic (git dft)

Structure:
- rename desktop -> konishi; homeConfigurations -> "user@host" for nh autodetect

Removals (heavy/unused):
- android-studio, unity/.NET/omnisharp/vscode, kicad, zoom, calibre,
  google-fonts, nerd-dictation

Screen recording:
- kooha + vokoscreen-ng + `webcam` corner-cam command/window-rule

Fixes:
- WEBKIT_DISABLE_DMABUF_RENDERER moved to common (electron/tauri on intel)
- kitty pinned to Catppuccin-Mocha; darkman no longer toggles kitty/claude
- claude theme dark + statusline locale fix
- ssh: migrate to settings API + multiplexing/keepalive/AddKeysToAgent;
  gpg-agent enableSshSupport
- silence hyprland configType / gtk4 / xdg userDirs deprecations

Flake hygiene:
- follows=nixpkgs for foundry/hardware/rose-pine/zen/spicetify (10->5 nixpkgs)
- zoxide _ZO_DOCTOR=0

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

flake.nix

@@ -26,11 +26,24 @@
     };
     foundry = {
       url = "github:shazow/foundry.nix";
+      inputs.nixpkgs.follows = "nixpkgs";
     };
-    hardware.url = "github:NixOS/nixos-hardware/master";
-    rose-pine-hyprcursor.url = "github:ndom91/rose-pine-hyprcursor";
-    zen-browser.url = "github:0xc000022070/zen-browser-flake";
+    hardware = {
+      url = "github:NixOS/nixos-hardware/master";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    rose-pine-hyprcursor = {
+      url = "github:ndom91/rose-pine-hyprcursor";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    zen-browser = {
+      url = "github:0xc000022070/zen-browser-flake";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    # ethui pins its own nixpkgs (verified rust/tauri build) — do not follow.
     ethui.url = "github:ethui/ethui/nix";
+    # hyprland pins its own nixpkgs to match its cachix cache — do not follow,
+    # or it compiles from source.
     hyprland = {
       type = "git";
       url = "https://github.com/hyprwm/Hyprland";
@@ -40,7 +53,10 @@
       url = "github:noctalia-dev/noctalia-shell";
       inputs.nixpkgs.follows = "nixpkgs";
     };
-    spicetify-nix.url = "github:Gerg-L/spicetify-nix";
+    spicetify-nix = {
+      url = "github:Gerg-L/spicetify-nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
     claude-code.url = "github:sadjow/claude-code-nix";
     nix-index-database = {
       url = "github:nix-community/nix-index-database";