Bump to 0.3.0 with the audit, brand and command-rename changelog

Phase 2 of the audit follow-ups, the Hellion Online Media brand
sweep and the rename of the slash commands all land in one release.
The slash command rename is breaking for users who had macros bound
to /chat2, /chat2Viewer or /clearlog2, which is the main reason
this is a 0.3.0 rather than a 0.2.1.

csproj, plugin manifest yaml, custom-repo repo.json (assembly
version, testing assembly version and the three download links)
and the README version banner are all moved over together so the
Dalamud plugin list, the manifest and the install instructions
agree. The README project status checklist is updated to reflect
that Phase 2 is closed; Phase 3 holds the remaining backlog
(MySQL backend, encryption, libnotify, etc).

The yaml and repo.json changelogs gain a 0.3.0 block that walks
through the four substantial groups of changes (slash command
rename, audit hardening, brand sweep, About tab) in plain prose.
The 0.2.0 block stays underneath in chronological order.

Build (Release) verified — ChatTwo/bin/Release/HellionChat/latest.zip
(~17.5 MB) and HellionChat.json regenerate cleanly with no warnings.
The tag itself is created by hand alongside the GitHub release.

ChatTwo/HellionChat.yaml

@@ -40,6 +40,67 @@ tags:
   - Replacement
   - Privacy
 changelog: |-
+  **Hellion Chat 0.3.0 — Audit hardening, brand sweep and rebrand of slash commands**
+
+  This release closes the remaining audit follow-ups from the
+  0.2.0 cleanup and finishes turning Hellion Chat into a properly
+  branded fork rather than a Chat 2 with a different name.
+
+  Slash commands have been renamed across the board so they no
+  longer collide with the upstream plugin and tell you which
+  plugin owns them at a glance:
+
+  - /chat2          becomes /hellion
+  - /chat2Viewer    becomes /hellionView
+  - /clearlog2      becomes /clearhellion
+  - /chat2Debugger  becomes /hellionDebugger (internal)
+  - /chat2SeString  becomes /hellionSeString (internal)
+
+  This is a breaking change for anyone with macros bound to the
+  old command names. The upstream Chat 2 commands keep working
+  if you also have that plugin installed.
+
+  Privacy and storage hardening based on the post-0.2.0 audit:
+
+  - Privacy filter master switch now states explicitly that the
+    filter only governs storage, not the live chat log
+  - Emote cache refuses to write outside its own directory if a
+    third-party API ever returns a path that escapes
+  - Retention sweep is serialised so the 24h auto-sweep and the
+    manual button cannot launch in parallel and race for the
+    SQLite connection
+  - DbViewer paging uses an int constant and the matching SQL
+    parameter name (the upstream code passed a float and a name
+    without the parameter prefix; both worked in practice but
+    were inconsistent)
+
+  Visual identity now matches the Hellion Online Media website:
+
+  - Theme palette switched to Arctic Cyan plus Ember Orange,
+    matching the website's BRANDING.md tokens
+  - Active tabs and window title bars use a brand-color-dark teal
+    variation as identity colour, replacing the previous slate
+    violet that did not appear in the brand
+  - Resize grips and scrollbar grabs picked up Ember Orange
+    instead of industrial amber on hover and active states
+
+  About tab rewritten and properly localised:
+
+  - New "Why this fork exists" block sets out the mission in
+    neutral terms, framing Chat 2's full-history default as the
+    right one for most users while explaining the narrower
+    default footprint this fork chose
+  - All Hellion-specific About copy now lives in HellionStrings
+    in EN and DE, so German users see the Hellion sections in
+    German rather than the upstream English fallback
+  - Webinterface absence is described as a focus mismatch
+    (different use case, substantial rebuild) rather than as
+    a security issue with the upstream code
+  - Translator list at the bottom of the About tab is reachable
+    again on smaller settings windows
+
+  Based on Chat 2 1.35.3 (upstream Infiziert90/ChatTwo, EUPL-1.2).
+
   **Hellion Chat 0.2.0 — Webinterface removed**
 
   The upstream webinterface has been removed in its entirety. It