docs: unify documentation and streamline code comments

- Translated project documentation (LEARNING-JOURNEY, CONTRIBUTORS, AI_DISCLOSURE) to English for better accessibility.
- Standardized internal code documentation by converting XML-doc blocks to standard comment format.
- Cleaned up inline comments and removed redundant versioning metadata across the codebase.
- Refactored non-functional text elements to improve readability and maintain a consistent style.

HellionChat/Privacy/PrivacyDefaults.cs

@@ -4,10 +4,9 @@ namespace HellionChat.Privacy;
 
 internal static class PrivacyDefaults
 {
-    // Privacy-First default whitelist (DSGVO Art. 25 - Privacy by Default).
-    // Only the player's own conversations are persisted out-of-the-box.
-    // Public chat (Say/Shout/Yell), Novice Network, NPC dialogue, system
-    // logs and battle messages are NOT persisted unless the user opts in.
+    // DSGVO Art. 25 (Privacy by Default): only the player's own conversations
+    // are persisted out-of-the-box. Public chat, NPC dialogue, system logs and
+    // battle messages require explicit opt-in.
     internal static readonly IReadOnlySet<ChatType> PrivacyFirstWhitelist = new HashSet<ChatType>
     {
         ChatType.TellIncoming,
@@ -42,10 +41,8 @@ internal static class PrivacyDefaults
         ChatType.ExtraChatLinkshell8,
     };
 
-    // Default retention windows per channel (in days). Channels not listed
-    // here fall back to Configuration.RetentionDefaultDays. Reflects the
-    // design spec: Tells 365, own-conversation channels 90, everything else
-    // shorter via the global default.
+    // Per-channel retention in days. Unlisted channels fall back to
+    // Configuration.RetentionDefaultDays. Tells: 365, everything else: 90.
     internal static readonly IReadOnlyDictionary<ChatType, int> DefaultRetentionDays =
         new Dictionary<ChatType, int>
         {
@@ -86,10 +83,9 @@ internal static class PrivacyDefaults
             [ChatType.ExtraChatLinkshell8] = 90,
         };
 
-    // Casual profile = Privacy-First plus public chat (Say/Shout/Yell, both
-    // emote types, Novice Network), kept for a short 24-hour window so the
-    // last RP scene or shout trade is still searchable but third-party data
-    // doesn't accumulate forever.
+    // Casual: Privacy-First + public chat (Say/Shout/Yell, emotes, Novice
+    // Network) with a 1-day window so recent RP/trade is searchable but
+    // third-party data doesn't accumulate.
     internal static readonly IReadOnlySet<ChatType> CasualWhitelist = new HashSet<ChatType>(
         PrivacyFirstWhitelist
     )