docs: hold the documentation against the code

Every claim in the user-facing docs, checked against what the plugin
actually does after A2 to A5.

The two GDPR sections in PRIVACY.md describe features that only exist
again as of this cycle, so they now name the screens they live on and
say what the cleanup does with a channel this build does not recognise.
The export sentence promised a date range; the form offers an age in
days.

PRIVACY.md also named "Show emotes" in Settings as the way to stop the
one outbound call the plugin makes. That switch has had no control since
May, and a documented opt-out that only exists in the JSON is not an
opt-out, so the toggle is back in the chat tab. Both its strings were
already translated.

Dead paths: the README source tree still listed a file deleted in May,
docs/IPC.md cited a window that no longer exists, the first-run wizard
pointed at the same removed file, and the theme authoring guide sent
readers to a Themes tab that is called Appearance.

The changelog lost two double blank lines that were failing markdownlint
and holding preflight red. Preflight is green again.

Historical documents keep their old paths on purpose: the changelog and
the AI disclosure describe what was true when they were written.

docs/IPC.md

@@ -169,8 +169,8 @@ the same tuple:
 `ChannelType` is the `HellionChat.Code.ChatType` enum value representing the target channel for the
 current submission. It is sourced from the active tab's `UsedChannel`
 (`HellionChat/Configuration.cs`), which the plugin keeps in sync by hooking the in-game shell
-(`HellionChat/GameFunctions/Chat.cs`) and by resolving temporary overrides inside the chat UI
-(`HellionChat/Ui/ChatLogWindow.cs:597`). `InputChannel` values are converted into the exported
+(`HellionChat/GameFunctions/Chat.cs`) and by resolving temporary overrides in the input bar
+(`HellionChat/Ui/Components/InputBar.cs`). `InputChannel` values are converted into the exported
 `ChatType` via `HellionChat/Code/InputChannelExt.ToChatType`.
 
 ### Behavior