docs(release): prepare 1.0.0-alpha.13

[iriswolf]

Summary

• move the completed Unreleased changes into the 1.0.0-alpha.13 changelog entry;
• document migration requirements for the new [FromUser] / [FromBot] semantics and removal of TelegramChatType.Sender;
• record Telegram Bot API 10.2 alignment and require applications to upgrade the package set together.

Release contents

• formatted Telegram text builders and escaping helpers;
• optional locale-resolution and Fluent localization packages;
• explicit sender-user, sender-bot, and sender-chat filter semantics;
• canonical Unicode matching for exact and template command routes;
• CI coverage report and pull-request workflow improvements.

Verification

• pwsh -NoProfile -File .\eng\verify-release.ps1 -PackageVersion 1.0.0-alpha.13 -Configuration Release -OutputDirectory .\artifacts\release-packages\1.0.0-alpha.13-verified
• Release build and strict analyzers: 0 warnings, 0 errors
• full test suite passed
• 15 runtime/tooling NuGet packages and 14 symbol packages produced
• package metadata and expected package set validation passed
• new i18n package dependency graph inspected
• git diff --check