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-forge/src/verbs/list.rs

@@ -8,6 +8,8 @@
 //! second of the four #694 gaps (read-side; no boundary concerns —
 //! every agent + the operator queries the issue tracker constantly).
 
+use std::fmt::Write as _;
+
 use anyhow::Result;
 use clap::{Args as ClapArgs, ValueEnum};
 use serde_json::Value;
@@ -97,24 +99,24 @@ pub fn run(client: &Client, args: Args) -> Result<()> {
     if let Some(u) = args.assignee.as_deref()
         && !u.is_empty()
     {
-        path.push_str(&format!("&assigned_by={}", pct_encode(u)));
+        write!(path, "&assigned_by={}", pct_encode(u)).unwrap();
     }
     if let Some(u) = args.author.as_deref()
         && !u.is_empty()
     {
-        path.push_str(&format!("&created_by={}", pct_encode(u)));
+        write!(path, "&created_by={}", pct_encode(u)).unwrap();
     }
     if let Some(u) = args.mention.as_deref()
         && !u.is_empty()
     {
-        path.push_str(&format!("&mentioned_by={}", pct_encode(u)));
+        write!(path, "&mentioned_by={}", pct_encode(u)).unwrap();
     }
     if !args.labels.is_empty() {
         // Encode each label individually so a comma INSIDE a label
         // (rare but legal) gets escaped while the field separator
         // stays a literal comma the forge will parse as N labels.
         let encoded: Vec<String> = args.labels.iter().map(|l| pct_encode(l)).collect();
-        path.push_str(&format!("&labels={}", encoded.join(",")));
+        write!(path, "&labels={}", encoded.join(",")).unwrap();
     }
     let resp = client.get_json(&path)?;
     if client.json_mode() {
@@ -143,7 +145,7 @@ fn pct_encode(s: &str) -> String {
         if b.is_ascii_alphanumeric() || matches!(b, b'-' | b'_' | b'.' | b'~') {
             out.push(b as char);
         } else {
-            out.push_str(&format!("%{b:02X}"));
+            write!(out, "%{b:02X}").unwrap();
         }
     }
     out