docs: log v1.4.6 release notes

CHANGELOG.md gets the full per-bullet block, ROADMAP.md gets the
released-cycle summary plus a v1.4.7 next-cycle placeholder, README
status section and version badge updated.

docs/CHANGELOG.md

@@ -10,6 +10,50 @@ to the release pages for details.
 
 ---
 
+## Hellion Chat 1.4.6 — Code Hygiene and Refactor (2026-05-12)
+
+Maintenance patch. No user-visible behaviour changes; tightens the development feedback loop, fixes two
+upstream-inherited bugs from ChatTwo `f35b7d3`, and prepares the code for the v1.4.7 backlog cleanup.
+
+- `scripts/preflight.sh` gains Block E (`dotnet csharpier check`) and Block F (`markdownlint-cli2`) so reflow drift and
+  markdown violations are caught at the pre-push gate. `.markdownlint.json` adds `MD024 siblings_only` and disables
+  `MD036` so the bilingual forge-post bold-emphasis headings pass linting; the `.claude/` directory is excluded from the
+  scan
+- `FontManager.AddFontWithFallback` catch-filter now covers `InvalidOperationException` and `ArgumentException` on top
+  of the existing IO triad. The warning log carries the exception type name, so the diagnostic path knows which class
+  of atlas-toolkit throw triggered the NotoSansCjkRegular fallback
+- `BrandingLinks` (5 URLs) and `Integrations/IntegrationLinks` (2 URLs) validate themselves on first module load via
+  `[ModuleInitializer]` + a shared `UrlValidation.ValidateAll` helper. A malformed URL now throws
+  `InvalidOperationException` at plugin load with the source class and the broken URL in the message
+- Cherry-picked from ChatTwo upstream `f35b7d3`: `Chat.SetChannel` no longer leaks the native `Utf8String` when the
+  linkshell check rejects the channel. The validity check is now wrapped around the `ChangeChatChannel` call instead of
+  short-circuiting before `Dtor`. `ValidAnyLinkshell` is renamed to `IsChannelOrExistingLinkshell` and the
+  `ChatLogWindow` call-site follows the rename
+- Cherry-picked from ChatTwo upstream `f35b7d3`: `Tab.Clone` now deep-clones `UsedChannel` and `TellTarget`. The old
+  `CurrentChannel = CurrentChannel` was a reference copy, so PopOut and Temp tabs mutated each other's channel state
+  (incl. tell target). `TellTarget.From(t)` static factory is replaced with an instance `Clone()`; `UsedChannel.Clone()`
+  is new and runs deep-clone on both TellTarget references
+- `ChatLogWindow` active-tab underline pill now scales with `ImGuiHelpers.GlobalScale` and rounds its DrawList
+  coordinates to physical pixels via `MathF.Round`, so the 2 px line stays crisp on 125 % and 150 % DPI setups instead
+  of bleeding into a sub-pixel blur
+- `ImGuiUtil.IconButton` width parameter no longer subtracts HUD-scaled `CellPadding.X * 2` from the raw `int` width.
+  `ImGui.Button` handles its own frame padding internally, so the measured `buttonWidth` now passes through verbatim
+  (inspired-by upstream `f35b7d3`, but our two call-sites need the parameter, so the param itself stays)
+- Internal: `HellionStyle` ChildBgAlpha threshold logic extracted to `HellionStyleHelpers.ResolveChildBgAlpha` with a
+  build-suite mirror test that pins the 0.999f cutoff. `Plugin.SaveConfig` clones only the temp-tab subset in the
+  pre-serialization snapshot instead of the full tab list. `SettingsOverview` caches `ImGui.GetWindowDrawList()` once
+  per frame and passes the pointer down to `DrawCard`
+- Internal: `Dalamud.Utility.Util` static surface (`IsWine`, `OpenLink`) routed through a new `IPlatformUtil`
+  indirection. `MessageStore`'s `IsWine` probe is now reachable from the xUnit AppDomain via a `FakePlatformUtil`
+  fixture (full isolated MessageStore construction still pending — `Plugin.Log.Information` in `Migrate0` is a separate
+  Dalamud-static surface, slated for v1.4.7)
+
+Modding & support: join Hellion Forge — <https://discord.gg/X9V7Kcv5gR>
+
+Based on Chat 2 1.35.3 (upstream Infiziert90/ChatTwo, EUPL-1.2).
+
+---
+
 ## Hellion Chat 1.4.5 — UX and Robustness (2026-05-12)
 
 Sixth sub-patch of the v1.4.x polish-sweep series. User-visible robustness fixes plus two doc/test polish items from the