chore: complete deprecate nimbus-build-system

.gitmodules

@@ -1,8 +1,3 @@
-[submodule "vendor/nimbus-build-system"]
-	path = vendor/nimbus-build-system
-	url = https://github.com/status-im/nimbus-build-system.git
-	ignore = untracked
-	branch = master
 [submodule "vendor/nim-chronos"]
 	path = vendor/nim-chronos
 	url = https://github.com/status-im/nim-chronos.git

README.md

@@ -32,8 +32,7 @@ nix build --print-out-paths '.?submodules=1#libsds-android-x86'
 nix build --print-out-paths '.?submodules=1#libsds-android-arm'
 ```
 
-<details>
-<summary>Development shell</summary>
+### Development shell
 
 Enter the dev shell (sets up vendored dependencies automatically):
 ```bash
@@ -62,10 +61,7 @@ nim test sds.nims
 
 The built library is output to `build/`.
 
-</details>
-
-<details>
-<summary>Android (without Nix)</summary>
+### Android (without Nix)
 
 Download the latest Android NDK. For example, on Ubuntu with Intel:
 
@@ -101,8 +97,6 @@ ARCH=arm64 ANDROID_ARCH=aarch64-linux-android ARCH_DIRNAME=aarch64-linux-android
 
 The library is output to `build/libsds.so`.
 
-</details>
-
 ## Maintenance
 
 ```bash

nix/default.nix

@@ -1,8 +1,6 @@
 {
   pkgs,
   src ? ../.,
-  # Nimbus-build-system package (used only for pinned Nim compiler).
-  nim ? null,
   # Options: 0,1,2
   verbosity ? 2,
   # Build targets (e.g., ["libsds"], ["libsds-android-arm64"])

nix/shell.nix

@@ -1,6 +1,5 @@
 {
   pkgs ? import <nixpkgs> { },
-  nim ? null,
 }:
 
 let