chore(release): bump assembly version to 1.10.0

Style foundation cycle closed. Smoke tests green across the sidebar, the tab
strip, the status bar, the theme preview and both message densities.

Download links stay on v1.5.6 deliberately: v1.6.0 through v1.10.0 are local
development states and nobody should update into one. The README badge stays
there too, since it points at the published release.

The roadmap now reflects the actual sequence -- the old "next cycle" entry
still named v1.5.7 ad-block, which has been behind the v2.x UI rebuild since
May.

Verified file by file: csproj, repo.json (both assembly versions, links
untouched), CHANGELOG, ROADMAP. Four TODOs remain in the tree, all pre-existing
and none from this cycle.

repo.json

@@ -3,7 +3,7 @@
         "Author": "Jon Kazama (Hellion Forge)",
         "Name": "Hellion Chat",
         "InternalName": "HellionChat",
-        "AssemblyVersion": "1.9.0.0",
+        "AssemblyVersion": "1.10.0.0",
         "Description": "A Hellion Forge plugin — privacy-focused chat replacement for FINAL FANTASY XIV, built for EU, US and JP data rules.\n\nBy default only your own conversations are stored. Public chat, NPC dialogue, system messages and battle logs are discarded at the storage layer unless you opt in. Retention windows are configurable per channel, history can be wiped retroactively, and everything can be exported on demand.\n\nFeatures:\n- Channel whitelist with a Privacy-First default\n- Per-channel retention with a daily background sweep\n- Retroactive cleanup with preview and Ctrl+Shift confirm\n- Export to Markdown, JSON or CSV\n- First-run wizard with four profiles: Privacy-First, Casual, Roleplay, Full History\n- Multi-language UI (24 locales) with live language switching\n- Own config and database — no shared state with other plugins\n\nBased on Chat 2 by Infi and Anna (EUPL-1.2).\nSupport: https://discord.gg/X9V7Kcv5gR",
         "ApplicableVersion": "any",
         "RepoUrl": "https://gitea.hellion-forge.cloud/JonKazama-Hellion/HellionChat",
@@ -25,7 +25,7 @@
         "DownloadLinkInstall": "https://gitea.hellion-forge.cloud/JonKazama-Hellion/HellionChat/releases/download/v1.5.6/latest.zip",
         "DownloadLinkUpdate": "https://gitea.hellion-forge.cloud/JonKazama-Hellion/HellionChat/releases/download/v1.5.6/latest.zip",
         "DownloadLinkTesting": "https://gitea.hellion-forge.cloud/JonKazama-Hellion/HellionChat/releases/download/v1.5.6/latest.zip",
-        "TestingAssemblyVersion": "1.9.0.0",
+        "TestingAssemblyVersion": "1.10.0.0",
         "IconUrl": "https://gitea.hellion-forge.cloud/JonKazama-Hellion/HellionChat/raw/branch/main/HellionChat/images/icon.png",
         "ImageUrls": [
             "https://gitea.hellion-forge.cloud/JonKazama-Hellion/HellionChat/raw/branch/main/HellionChat/images/chatWindow.png",