docs: add v1.4.9 changelog and forge announcement post

Synchronises the v1.4.9 changelog across the manifest sources that the
Dalamud plugin installer, the gitea repo.json feed and the Forge auto-
announce workflow read at release-tag time.

Files touched:
- HellionChat/HellionChat.yaml: v1.4.9 block inserted at the top of the
  changelog: literal. v1.4.5 dropped to keep the slim-rule at 4 subblocks
  (preflight Block C enforces YAML_VERSIONS <= 4). Current set is
  v1.4.9/v1.4.8/v1.4.7/v1.4.6.
- repo.json: Changelog field kept synchronous with the yaml — v1.4.9
  block prepended, v1.4.5 substring removed, JSON-escaped newlines.
- .github/forge-posts/v1.4.9.md: new file with frontmatter (subtitle
  "Plugin-Load Render Polish", versionsnatur "Performance-Patch") and
  a German-only body. The English half of the eventual Discord embed
  is pulled automatically from the yaml changelog at tag-push time by
  .gitea/workflows/forge-announce.yml — same workflow as v1.4.4
  onwards, the post file does not carry an English block.

Char-cap pre-check passes (title 46 + description ~2700 + footer 33 =
~2800 chars, well under the 5500-char Discord embed total cap).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

HellionChat/HellionChat.yaml

@@ -35,6 +35,33 @@ tags:
     - Replacement
     - Privacy
 changelog: |-
+    **v1.4.9 — Plugin-Load Render Polish (2026-05-15)**
+
+    Tenth sub-patch of the v1.4.x polish-sweep series. First-frame
+    render cost drops from ~127 ms median to ~76 ms median,
+    comfortably under Dalamud's 100 ms HITCH warning threshold.
+
+    - First-frame defer: six non-essential rendering sections inside
+      ChatLogWindow skip their first Draw and run one frame later
+      (bottom status bar, channel-name SeString chunks, window bounds
+      check, v0.6.1 hint banner, autocomplete, input-preview
+      calculation). User-visible delay is ~17 ms at 60 fps, hidden
+      inside the post-reload font-atlas build window.
+    - Slash-command centralisation: /hellion, /hellionView,
+      /hellionSeString and /hellionDebugger are registered in
+      LoadAsync instead of inside the corresponding window
+      constructors. The plugin-manager Open and configuration buttons
+      hang on the same path.
+    - Plugin-load profiling logs stay on at Information level
+      (MessageStore connect/migrate, FilterAllTabs, auto-translate
+      warmup) as a regression tripwire — a future load past 100 ms
+      will show up in /xllog without a Debug filter.
+    - Migration v17 stays (no schema bump).
+
+    Based on Chat 2 1.35.3 (upstream Infiziert90/ChatTwo, EUPL-1.2).
+
+    ---
+
     **v1.4.8 — Hook-Layer and Polish Quick-Wins (2026-05-14)**
 
     Ninth sub-patch of the v1.4.x polish-sweep series. Hook-layer
@@ -151,27 +178,4 @@ changelog: |-
 
     ---
 
-    **v1.4.5 — UX and Robustness (2026-05-12)**
-
-    Sixth sub-patch of the v1.4.x polish-sweep series. Chat-log draw
-    failures surface as a notification, the first-run wizard has an
-    explicit "Later" option, the input history clears on plugin reload,
-    and the status bar version slot stops clipping in narrow windows.
-
-    - Chat window draw errors now show a one-shot notification instead
-      of failing silently — stack trace stays in /xllog
-    - First-run wizard: explicit "Later — keep defaults" button.
-      Closing the X no longer silently accepts the defaults; the wizard
-      reopens on the next plugin load if nothing was picked
-    - InputHistoryService clears on plugin dispose so the previous
-      session's typed commands don't bleed into the next load
-    - Status bar hides the version slot when the chat window is too
-      narrow to fit all five slots without overlap
-    - Internal: explicit session-only Auto-Tell-Tab invariant in
-      Plugin.cs plus a pinning test in the Build-Suite
-    - Internal: FontManager falls back to the system font if the
-      embedded Hellion font resource is missing — logs a Warning
-
-    ---
-
     Full history: https://gitea.hellion-forge.cloud/JonKazama-Hellion/HellionChat/releases