Restore LICENSE.txt (wiped by 26.5.0 snapshot-promote)

[fahadadeel]

What

Restores LICENSE.txt (MIT, Aspose Pty Ltd, 2001-2026) which was on main at commit 5fe6164b6 (Jun 10) but never lived on release/26.5.0. The snapshot-promote (8acbf18a) set main's tree to release's tree → wiped the file.

Why this happened

Release branches are orphans of main — Phase 2b in run_version_bump() only seeds .github/ from main, nothing else. So files added to main after the release branch is created (like LICENSE.txt was) don't propagate to the release tree, and a snapshot-promote then wipes them from main.

Permanent fix is a follow-up MR on the generator (extend Phase 2b to seed a configurable file list; add a pre-promote guardrail that aborts when files would be wiped). This PR just restores what was lost.

Validation

• File content fetched directly from the original commit 5fe6164b6 via the contents API — byte-for-byte identical
• No .cs diff so the Build & Run changed examples workflow will short-circuit