ChessRealms.Engine 1.2.0

What's Changed

• feat(san): support canonical move formatting and parsing by @denyrt in #15
• feat(pgn): add mainline import and export with diagnostics by @denyrt in #16
• perf(engine): optimize FEN, repetition tracking, and game import/export by @denyrt in #17
• chore: move version to 1.2.0, nuget badge for readme by @denyrt in #18
• ci: new package description by @denyrt in #19

Full Changelog: v1.1.0...v1.2.0