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-ag3nt/src/mcp.rs

@@ -448,20 +448,20 @@ fn format_bash_status(id: &str) -> String {
         let age = crate::serve_common::now_unix() - t;
         let _ = write!(out, ", running for {age}s");
     }
-    if let Some(t) = task.completed_at {
-        if let Some(s) = task.started_at {
-            let _ = write!(out, ", took {}s", t - s);
-        }
+    if let Some(t) = task.completed_at
+        && let Some(s) = task.started_at
+    {
+        let _ = write!(out, ", took {}s", t - s);
     }
-    if let Some(ref stdout) = task.stdout_tail {
-        if !stdout.trim().is_empty() {
-            let _ = write!(out, "\n\nstdout:\n```\n{}\n```", stdout.trim());
-        }
+    if let Some(ref stdout) = task.stdout_tail
+        && !stdout.trim().is_empty()
+    {
+        let _ = write!(out, "\n\nstdout:\n```\n{}\n```", stdout.trim());
     }
-    if let Some(ref stderr) = task.stderr_tail {
-        if !stderr.trim().is_empty() {
-            let _ = write!(out, "\n\nstderr:\n```\n{}\n```", stderr.trim());
-        }
+    if let Some(ref stderr) = task.stderr_tail
+        && !stderr.trim().is_empty()
+    {
+        let _ = write!(out, "\n\nstderr:\n```\n{}\n```", stderr.trim());
     }
     out
 }
@@ -1913,14 +1913,14 @@ pub enum Flavor {
 }
 
 /// Env var written by the meta renderer with a comma-separated list of
-/// `hive_sh4re::ToolGroup` snake_case names (e.g. `"messaging,inbox,meta"`).
+/// `hive_sh4re::ToolGroup` `snake_case` names (e.g. `"messaging,inbox,meta"`).
 /// When present, the harness expands the groups into per-tool allow entries
 /// instead of using the hardcoded flavor default. See `docs/conventions.md::Tool groups`.
 const TOOL_GROUPS_ENV: &str = "HIVE_TOOL_GROUPS";
 
 /// `HIVE_CAPABILITIES` env var injected by `meta::render_flake` when the
 /// operator grants capabilities to this agent. Comma-separated
-/// `hive_sh4re::Capability` snake_case names. Absent = no extra capabilities.
+/// `hive_sh4re::Capability` `snake_case` names. Absent = no extra capabilities.
 const CAPABILITIES_ENV: &str = "HIVE_CAPABILITIES";
 
 /// Returns the MCP tool names (without `mcp__hyperhive__` prefix) that are
@@ -1976,14 +1976,12 @@ fn effective_tool_groups(flavor: Flavor) -> Vec<hive_sh4re::ToolGroup> {
     for token in raw.split(',') {
         let t = token.trim().to_ascii_lowercase();
         // Parse via serde_json (the canonical deserialization path).
-        match serde_json::from_value::<hive_sh4re::ToolGroup>(
+        if let Ok(g) = serde_json::from_value::<hive_sh4re::ToolGroup>(
             serde_json::Value::String(t.clone()),
         ) {
-            Ok(g) => groups.push(g),
-            Err(_) => tracing::warn!(
-                token = %t,
-                "{TOOL_GROUPS_ENV}: unknown tool group, skipping"
-            ),
+            groups.push(g);
+        } else {
+            tracing::warn!(token = %t, "{TOOL_GROUPS_ENV}: unknown tool group, skipping");
         }
     }
     if groups.is_empty() {