chore(fontmanager): drop unused Lodestone font download

The FontManager constructor downloaded FFXIV_Lodestone_SSF.ttf from
img.finalfantasyxiv.com on first start (or read it from a local
cache) into a GameSymFont byte array. Both historical readers of
that field are gone:

- BuildFonts() used to feed the bytes into AddFontFromMemory; that
  path was replaced by the Dalamud-provided AddGameSymbol helper.
- The upstream webinterface server wrote the bytes through a
  BinaryWriter to serve them to the Svelte frontend; the entire
  webinterface was intentionally removed in HellionChat.

With no live consumer left, the field, the constructor block, the
HttpClient call and the disk cache are all dead code. Removing them:

- eliminates the synchronous HTTP request on the plugin-load thread
  (no more multi-second startup hang on slow networks)
- closes the implicit "no timeout, no size guard" exposure on that
  request
- removes one outbound network endpoint (Square Enix Lodestone CDN)
  from the privacy footprint

PRIVACY.md and THIRD_PARTY_NOTICES.md updated to reflect that
HellionChat now talks to BetterTTV only (opt-out via setting). Cached
TTF files left over from earlier versions stay in pluginConfigs/
HellionChat/ until a user removes them; they are simply no longer
read.

Build: 0 warnings, 0 errors. No behavioural change for users — symbol
glyphs (job icons, item glyphs, status effects) keep rendering through
Dalamud's built-in symbol font.

docs/THIRD_PARTY_NOTICES.md

@@ -64,8 +64,10 @@ traffic is initiated explicitly by HellionChat's own source files
 and is documented in `PRIVACY.md` under "Outbound network calls":
 
 - `HellionChat/EmoteCache.cs` → BetterTTV API + CDN (opt-out via setting)
-- `HellionChat/FontManager.cs` → Square Enix Lodestone font CDN (one-time
-  download)
+
+The earlier Square Enix Lodestone font download (`FontManager.cs`)
+was removed in v1.0.4 — it was a leftover from upstream's removed
+webinterface feature and was no longer consumed.
 
 ---