fix(clippy): fix all clippy warnings in hive-ag3nt, hive-forge, hive-matrix-mcp, hive-sh4re

Fixes all clippy -D warnings errors in the crates iris owns:

hive-sh4re:
- doc_lazy_continuation: add blank /// separator in priv_proto.rs
- doc_markdown: backtick PRIVATE_NETWORK=0 / PRIVATE_NETWORK=1

hive-matrix-mcp:
- map_unwrap_or: map().unwrap_or_else() -> map_or_else() in paths.rs
- collapsible_if: if-let chains in wake.rs
- doc_markdown: backtick M_UNKNOWN_TOKEN in main.rs
- cast_possible_truncation: usize/u64 -> u32::try_from in handlers.rs
- map_unwrap_or: map_or_else() in handlers.rs
- manual_let_else: match Ok(r) => r, Err => return -> let Ok in handlers.rs
- unused_async: remove async from list_invites; update socket.rs call site

hive-forge:
- doc_markdown: backtick REQUEST_CHANGES / APPROVED / COMMENT in pr_reviews.rs
- unnecessary_wraps: list_reviews_text returns () not Result<()>
- doc_markdown: backtick start_page / last_page in comments.rs
- cast_possible_truncation: PAGE_SIZE u64 -> usize; remove as usize casts

hive-ag3nt:
- collapsible_if: if-let chains in events.rs and mcp.rs
- single_match_else: match -> if let in events.rs and mcp.rs
- items_after_statements: hoist STATUS_MAX_CHARS const in mcp.rs
- map_unwrap_or: map_or_else() in mcp.rs and mcp_loose_ends.rs
- cast_possible_truncation: usize -> u32::try_from in mcp.rs
- doc_markdown: backtick snake_case in mcp.rs, needs_update/deployed_sha
  in web_ui.rs, HISTORY_CAPACITY in web_ui.rs
- identical_match_arms: combine manage_root_agent | query_agent_state
- redundant_closure: |s| s.to_string() -> ToString::to_string in web_ui.rs
- duration_suboptimal_units: from_secs(3600) -> from_hours(1) in turn.rs

Remaining failures in hive-c0re (39), hive-priv (8), hive-bash-mcp (11)
are owned by damocles.

hive-ag3nt/src/web_ui.rs

@@ -579,7 +579,7 @@ async fn api_state(State(state): State<AppState>) -> axum::Json<StateSnapshot> {
 /// fetches this once per running agent to get fresh, agent-authoritative
 /// values instead of relying on hive-c0re's periodic file-reads.
 ///
-/// Structural fields (running, needs_update, deployed_sha, parent, …)
+/// Structural fields (running, `needs_update`, `deployed_sha`, parent, …)
 /// continue to come from hive-c0re's `/api/state`; this endpoint covers
 /// only the fields the agent itself is the source of truth for.
 #[derive(serde::Serialize)]
@@ -808,7 +808,7 @@ struct HistoryParams {
     /// Cursor: only return events with sqlite row id < `before`.
     /// Omit for the initial (most-recent) page.
     before: Option<i64>,
-    /// Page size (default 100, capped at HISTORY_CAPACITY).
+    /// Page size (default 100, capped at `HISTORY_CAPACITY`).
     limit: Option<usize>,
 }
 
@@ -1094,7 +1094,7 @@ fn available_models() -> Vec<String> {
     const DEFAULT: &[&str] = &["haiku", "sonnet", "opus"];
     let raw = match std::env::var("HIVE_AVAILABLE_MODELS") {
         Ok(v) if !v.trim().is_empty() => v,
-        _ => return DEFAULT.iter().map(|s| s.to_string()).collect(),
+        _ => return DEFAULT.iter().map(ToString::to_string).collect(),
     };
     let models: Vec<String> = raw
         .split(',')
@@ -1102,7 +1102,7 @@ fn available_models() -> Vec<String> {
         .filter(|s| !s.is_empty())
         .collect();
     if models.is_empty() {
-        DEFAULT.iter().map(|s| s.to_string()).collect()
+        DEFAULT.iter().map(ToString::to_string).collect()
     } else {
         models
     }