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/container_view.rs

@@ -217,12 +217,12 @@ fn read_dashboard_links(name: &str) -> Vec<DashboardLink> {
 /// don't lose state during the transition window.
 fn read_harness_flags(name: &str) -> (bool, bool) {
     let dir = Coordinator::agent_notes_dir(name);
-    if let Ok(raw) = std::fs::read_to_string(dir.join("hyperhive-harness.json")) {
-        if let Ok(v) = serde_json::from_str::<serde_json::Value>(&raw) {
-            let rl = v.get("rate_limited").and_then(|x| x.as_bool()).unwrap_or(false);
-            let nl = v.get("needs_login").and_then(|x| x.as_bool()).unwrap_or(false);
-            return (rl, nl);
-        }
+    if let Ok(raw) = std::fs::read_to_string(dir.join("hyperhive-harness.json"))
+        && let Ok(v) = serde_json::from_str::<serde_json::Value>(&raw)
+    {
+        let rl = v.get("rate_limited").and_then(serde_json::Value::as_bool).unwrap_or(false);
+        let nl = v.get("needs_login").and_then(serde_json::Value::as_bool).unwrap_or(false);
+        return (rl, nl);
     }
     // Legacy fallback: presence of individual sentinel files.
     let rate_limited = dir.join("hyperhive-rate-limited").exists();