feat(service): expand service layer with new domain operations

- Add IM service modules: audit, channel roles, custom emojis, forum
  tags, integrations, invitations, repo links, slash commands, stages,
  voice, webhooks
- Add PR service modules: review requests, templates
- Add repo service modules: contributors, release assets, git extras
  (archive, branch rename, commit extras, diff/merge, tag, tree)
- Add user service: social (follow/block)
- Add internal auth service
- Update existing service modules with expanded functionality
- Remove deleted IM modules: articles, delivery trace, drafts,
  follows, messages, polls, presence, reactions, threads

service/im/util.rs

@@ -1,5 +1,6 @@
 pub use crate::service::util::{
-    clamp_limit_offset, ensure_affected, merge_optional_text, parse_enum, required_text, role_level,
+    clamp_limit_offset, ensure_affected, merge_optional_text, parse_enum, required_text,
+    role_level, set_local_user_id,
 };
 
 /// Maximum length for a channel name.
@@ -7,58 +8,3 @@ pub const MAX_CHANNEL_NAME: usize = 100;
 
 /// Maximum length for a channel topic.
 pub const MAX_CHANNEL_TOPIC: usize = 1024;
-
-/// Maximum length for a message body.
-pub const MAX_MESSAGE_BODY: usize = 4096;
-
-/// Maximum length for an article title.
-pub const MAX_ARTICLE_TITLE: usize = 256;
-
-/// Maximum number of poll options.
-pub const MAX_POLL_OPTIONS: usize = 10;
-
-/// Maximum length for a poll option text.
-pub const MAX_POLL_OPTION_TEXT: usize = 100;
-
-/// Redis key prefix for typing indicators.
-pub const TYPING_PREFIX: &str = "im:typing:";
-
-/// Redis key prefix for user presence.
-pub const PRESENCE_PREFIX: &str = "im:presence:";
-
-/// Redis TTL for typing indicators (seconds).
-pub const TYPING_TTL_SECS: usize = 8;
-
-/// Redis TTL for presence heartbeats (seconds).
-pub const PRESENCE_TTL_SECS: usize = 120;
-
-/// Maximum length for generated slugs.
-pub const MAX_SLUG_LEN: usize = 128;
-
-/// Generate a slug from a title string.
-pub fn slugify(title: &str) -> String {
-    let slug: String = title
-        .to_lowercase()
-        .chars()
-        .filter_map(|c| {
-            if c.is_ascii_alphanumeric() {
-                Some(c)
-            } else if c.is_whitespace() || !c.is_ascii() {
-                Some('-')
-            } else {
-                None
-            }
-        })
-        .collect::<String>()
-        .split('-')
-        .filter(|s| !s.is_empty())
-        .collect::<Vec<_>>()
-        .join("-");
-
-    let mut result = slug;
-    result.truncate(MAX_SLUG_LEN);
-    if result.ends_with('-') {
-        result.pop();
-    }
-    result
-}