docs/flake.lock: Update

Flake lock file updates:

• Updated input 'tgirlpkgs':
'path:../.?lastModified=0&narHash=sha256-6Jt8ZdEH0beONhU9ThbAmQsYlXCyzpmPpDkk6uPFqNM%3D' (1970-01-01)
→ 'path:../.?lastModified=0&narHash=sha256-NsShMXUII8vld3k6Ds4Cy/2pP%2Bip9G%2BnOvQX3DqVCVk%3D' (1970-01-01)
• Updated input 'tgirlpkgs/nixpkgs':
'https://releases.nixos.org/nixpkgs/nixpkgs-26.05pre914780.306ea70f9eb0/nixexprs.tar.xz?lastModified=1766314097&narHash=sha256-oYm/xATOdnAtxmFV/ztu7F96wdZT1GXRN6rZqlAVpPc%3D&rev=306ea70f9eb0fb4e040f8540e2deab32ed7e2055' (2025-12-21)
→ 'https://releases.nixos.org/nixpkgs/nixpkgs-26.05pre915678.cfc52a405c6e/nixexprs.tar.xz?lastModified=1766471942&narHash=sha256-7mq%2Bkpw4eDnEzeg2WoxCXaLvcnG8oNs0e/%2BKoDZX%2BP4%3D&rev=cfc52a405c6e85462364651a8f11e28ae8065c91' (2025-12-23)

docs/flake.lock

···
     },
     "nixpkgs_2": {
       "locked": {
-        "lastModified": 1766314097,
-        "narHash": "sha256-oYm/xATOdnAtxmFV/ztu7F96wdZT1GXRN6rZqlAVpPc=",
-        "rev": "306ea70f9eb0fb4e040f8540e2deab32ed7e2055",
+        "lastModified": 1766471942,
+        "narHash": "sha256-7mq+kpw4eDnEzeg2WoxCXaLvcnG8oNs0e/+KoDZX+P4=",
+        "rev": "cfc52a405c6e85462364651a8f11e28ae8065c91",
         "type": "tarball",
-        "url": "https://releases.nixos.org/nixpkgs/nixpkgs-26.05pre914780.306ea70f9eb0/nixexprs.tar.xz?lastModified=1766314097&rev=306ea70f9eb0fb4e040f8540e2deab32ed7e2055"
+        "url": "https://releases.nixos.org/nixpkgs/nixpkgs-26.05pre915678.cfc52a405c6e/nixexprs.tar.xz?lastModified=1766471942&rev=cfc52a405c6e85462364651a8f11e28ae8065c91"
       },
       "original": {
         "type": "tarball",
···
       },
       "locked": {
         "lastModified": 0,
-        "narHash": "sha256-6Jt8ZdEH0beONhU9ThbAmQsYlXCyzpmPpDkk6uPFqNM=",
+        "narHash": "sha256-NsShMXUII8vld3k6Ds4Cy/2pP+ip9G+nOvQX3DqVCVk=",
         "path": "../.",
         "type": "path"
       },