Bump to v0.1.2 with About-tab rebrand and Hellion-style README

Manifest moves to 0.1.2.0 so existing testers get an in-place
update offer once the matching GitHub release is published.

Changes since 0.1.1 are surface and packaging:

  - The inherited About tab now reflects the fork: Hellion Online
    Media as maintainer with hellion-media.de as the contact
    channel, EUPL-1.2 dual-copyright statement, FINAL FANTASY XIV
    SQUARE ENIX disclaimer, explicit acknowledgment of Chat 2 by
    Infi & Anna as the upstream foundation, and the original
    ChatTwo translator list relabelled as upstream Crowdin
    contributors so it isn't mistaken for Hellion translators.
  - Cherry-picked the upstream DBViewer UI improvements
    (auto-scroll-reset on page change, localized tooltips on the
    date reset, folder export, export-running notifications and
    the pagination arrows).
  - README rewritten in the Hellion project style: German prose,
    tech-stack table, architecture tree, database column list, a
    proper migration guide for users coming from Chat 2 (with
    Linux and Windows manual recovery commands), upstream-sync
    workflow notes for cherry-picks, project-status checklist
    separating bootstrap-done from phase-2-open work, and the
    Hellion Online Media footer.
  - repo.json regenerated to point at the v0.1.2 GitHub release
    asset URL.

Bundle changelog summarises the same so testers see the new
content in their plugin list before they pull the update.

ChatTwo/ChatTwo.csproj

@@ -4,7 +4,7 @@
              0.1.0 is our bootstrap release; the underlying Chat 2 base is
              called out in the yaml changelog so users can see what it
              derives from. -->
-        <Version>0.1.1</Version>
+        <Version>0.1.2</Version>
         <ImplicitUsings>enable</ImplicitUsings>
         <!-- HellionChat fork: assembly is renamed so Dalamud uses
              pluginConfigs/HellionChat instead of pluginConfigs/ChatTwo,