legal: font license texts on the ISO; permissive source-available MontaukOS license

- Ship each bundled font's license at 0:/os/licenses/: OFL-1.1 copies for
  JetBrains Mono, Noto Serif, and Roboto, and AGPLv3 + font-embedding
  exception for C059 (URW Base 35).
- THIRD-PARTY-NOTICES.txt gains sections for all four font families and
  now describes MontaukOS as source-available.
- license.txt rewritten as the MontaukOS Software License: use, study,
  modify, and redistribute freely with attribution; selling or bundling
  into commercial products still requires permission. Replaces the
  previous no-copy/no-modify/no-redistribute EULA.
- The MontaukOS license itself now also ships on the ISO
  (0:/os/licenses/LICENSE.txt, sourced from the website copy).
- man legal updated: license pointer + full third-party component list.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

programs/man/legal.7

@@ -3,9 +3,13 @@
     MontaukOS legal/copyright information
 
 .SH DESCRIPTION
-    Copyright (c) 2025-2026 Daniel Hammer, et al. All rights reserved.
+    Copyright (c) 2025-2026 Daniel Hammer, et al.
         (includes contributors to other projects, i.e. The Limine Bootloader. Please refer to any other project's own license.)
 
+    MontaukOS is source-available software, provided under the terms of the
+    MontaukOS Software License. The full license text is on this system at
+    0:/os/licenses/LICENSE.txt.
+
     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
     FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
@@ -37,6 +41,10 @@
     * Limine bootloader, Copyright (C) Mintsuki and contributors - BSD 2-Clause
     * BearSSL, Copyright (c) Thomas Pornin - MIT
     * stb_image, Copyright (c) Sean Barrett - MIT
+    * JetBrains Mono font, Copyright The JetBrains Mono Project Authors - OFL-1.1
+    * Noto Serif font, Copyright The Noto Project Authors - OFL-1.1
+    * Roboto font, Copyright The Roboto Project Authors - OFL-1.1
+    * C059 font (URW Base 35), Copyright (C) (URW)++ Design and Development
+      GmbH - AGPLv3 with font-embedding exception
 
-    Full license texts and notices are on this system in 0:/os/licenses/
-    (NOTICES.txt, GPL-2.0.txt, GPL-3.0.txt).
+    Full license texts and notices are on this system in 0:/os/licenses/.