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/comments.rs

@@ -48,8 +48,8 @@ pub struct Args {
 pub fn run(client: &Client, args: Args) -> Result<()> {
     let repo = client.repo();
     let comments = match args.tail {
-        Some(n) => fetch_tail(client, &repo, args.number, n)?,
-        None => fetch_head(client, &repo, args.number, args.limit)?,
+        Some(n) => fetch_tail(client, repo, args.number, n)?,
+        None => fetch_head(client, repo, args.number, args.limit)?,
     };
     if client.json_mode() {
         let trimmed: Vec<Value> = comments
@@ -99,6 +99,7 @@ fn fetch_head(client: &Client, repo: &str, number: u64, limit: u64) -> Result<Ve
 /// first to know how many exist, then start paginating from the
 /// page that contains item `total - n`. Work is bounded by
 /// `ceil(n/50) + 1` page fetches, regardless of thread length.
+#[allow(clippy::cast_possible_truncation)]
 fn fetch_tail(client: &Client, repo: &str, number: u64, n: usize) -> Result<Vec<Value>> {
     if n == 0 {
         return Ok(Vec::new());