fix(#999): resolve all clippy warnings across the workspace

All crates now pass `cargo clippy --workspace -- -D warnings` cleanly.

Fixes span six crates (hive-sh4re, hive-ag3nt, hive-c0re, hive-forge,
hive-priv, hive-matrix-mcp was already clean):

- doc_markdown: wrap snake_case, type names, constants in backticks
- collapsible_if / collapsible_match: fold nested ifs into let-chains
- duration_suboptimal_units: Duration::from_secs(N) → from_mins/from_hours
- implicit_hasher: allow on HashMap-param fns where generalization is risky
- items_after_statements: hoist use to function tops
- map(f).unwrap_or(x) → map_or(x, f); map(f).unwrap_or_else(g) → map_or_else
- is_ok_and / is_none_or in place of map().unwrap_or(bool)
- needless_continue: {} instead of continue in loop match arms
- match_same_arms: Ok(None) | Err(_) merged
- format_push_str: write!() instead of push_str(&format!())
- while let replaces loop { let Some(..) = x else { break } }
- struct_excessive_bools / dead_code: allow on purpose-built structs
- too_many_lines / too_many_arguments: allow where refactor not worth it
- unused_async: remove async from poll_once in bash_runner
- needless_borrow: fix &repo deref in hive-forge comments verb
- cast_possible_truncation: allow u64→usize in fetch_tail

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

hive-c0re/src/bash_tasks_vacuum.rs

@@ -23,7 +23,7 @@ use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
 use crate::coordinator::Coordinator;
 
-const VACUUM_INTERVAL: Duration = Duration::from_secs(3600);
+const VACUUM_INTERVAL: Duration = Duration::from_hours(1);
 /// Keep completed task files for 48 hours before sweeping them.
 const KEEP_SECS: i64 = 48 * 3600;
 
@@ -97,7 +97,7 @@ fn should_delete(json_path: &Path, cutoff: i64) -> bool {
     if !TERMINAL_STATUSES.contains(&status) {
         return false;
     }
-    let completed_at = v.get("completed_at").and_then(|t| t.as_i64()).unwrap_or(i64::MAX);
+    let completed_at = v.get("completed_at").and_then(serde_json::Value::as_i64).unwrap_or(i64::MAX);
     completed_at < cutoff
 }
 
@@ -106,10 +106,10 @@ fn should_delete(json_path: &Path, cutoff: i64) -> bool {
 fn delete_trio(dir: &Path, stem: &str) {
     for ext in ["json", "out", "err"] {
         let path = dir.join(format!("{stem}.{ext}"));
-        if path.exists() {
-            if let Err(e) = std::fs::remove_file(&path) {
-                tracing::warn!(path = %path.display(), error = ?e, "bash-tasks vacuum: remove failed");
-            }
+        if path.exists()
+            && let Err(e) = std::fs::remove_file(&path)
+        {
+            tracing::warn!(path = %path.display(), error = ?e, "bash-tasks vacuum: remove failed");
         }
     }
 }