docs: add v1.4.8 changelog and forge announcement post

- HellionChat.yaml: v1.4.8 changelog block above v1.4.7, v1.4.4
  dropped per slim-rule (verify-changelog-sync enforces max 4).
- repo.json: Changelog field synchronised with yaml, same slim-drop.
- .github/forge-posts/v1.4.8.md: bilingual announcement post (DE
  body, EN block resolved from yaml at workflow time). Frontmatter
  subtitle 32/60 chars, versionsnatur 12/40 chars, embed total
  ~2787/5500 chars.

HellionChat/HellionChat.yaml

@@ -35,6 +35,40 @@ tags:
     - Replacement
     - Privacy
 changelog: |-
+    **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
+    cluster (DbViewer FTS5 full-text search, ad-block foundation
+    investigation) plus three polish quick-wins.
+
+    - DbViewer full-text search: optional FTS5 index across the full
+      chat history. Built asynchronously on first load after the
+      update with a progress toast. The local page-filter remains
+      available as the default mode. Queries match as exact phrases
+      -- multi-word terms must appear together in order; advanced
+      users can opt into raw FTS5 MATCH syntax by wrapping their own
+      double-quotes.
+    - Custom theme files now auto-reload when edited while the theme
+      is active -- no need to re-click the theme in the picker.
+    - Retention sweep no longer blocks the framework thread, removing
+      the ~194ms mini-hitch per sweep.
+    - Status bar renders correctly at Windows display scaling > 100%.
+    - Receive-suppressed-tells routing investigated this cycle and
+      postponed to v1.5.x: when other plugins suppress tells via
+      CheckMessageHandled, the FFXIV chat pipeline skips the
+      RaptureLogModule.AddMsgSourceEntry path so HellionChat's
+      ContentIdResolverHook does not fire and tell-partner
+      identification breaks. The fix belongs next to the planned
+      ad-block hook layer where the same patch surface comes up.
+    - Internal: messages.Id is declared BLOB but stored as TEXT
+      (Microsoft.Data.Sqlite Guid binding). FTS bulk insert and
+      LoadByGuids match the TEXT storage form on both sides.
+      Migration v17 stays (no schema bump).
+
+    Based on Chat 2 1.35.3 (upstream Infiziert90/ChatTwo, EUPL-1.2).
+
+    ---
+
     **v1.4.7 — Backlog Cleanup and Mid-Features (2026-05-13)**
 
     Eighth sub-patch of the v1.4.x polish-sweep series. First
@@ -140,24 +174,4 @@ changelog: |-
 
     ---
 
-    **v1.4.4 — Threading and IPC safety polish (2026-05-12)**
-
-    Fifth sub-patch of the v1.4.x polish-sweep series. Threading
-    assumptions are documented per-method, a hot-path lock falls
-    away, and the privacy filter speaks up when an unknown ChatType
-    shows up.
-
-    - AutoTellTabs hot-path getter uses an Interlocked counter
-      instead of taking the lock on every read
-    - Honorific integration: per-method threading banners, plus
-      Warning-level log on unsubscribe failure
-    - AutoTranslate warmup thread marked IsBackground so plugin
-      unload doesn't wait for it
-    - PrivacyFilter logs once per unknown ChatType so a future
-      patch's added channel doesn't drop off the radar
-    - New installs persist unknown channels by default; existing
-      configs keep their explicit choice
-
-    ---
-
     Full history: https://gitea.hellion-forge.cloud/JonKazama-Hellion/HellionChat/releases