clippy: fix lints that crane's cargoClippy properly enforces (#538)

The naersk → crane swap in the parent commit flips clippy from
silently passing to actually failing on `-D warnings` (naersk's
`mode = "clippy"` mangled the `--` separator so the deny never took
effect). This commit clears the surfaced lints so the workspace
builds clean under the new enforcement — every fix is mechanical and
preserves behaviour. Tests still pass (160 across the workspace).

Auto-fixes via `cargo clippy --fix`:
- `doc_markdown` (19 sites): bare identifiers in doc comments
  wrapped in backticks
- `format_in_format_args`, `explicit_into_iter_loop`,
  `redundant_closure_for_method_calls`, `useless_conversion`, and
  a few more — mechanical rewrites of the kind cargo can apply
  safely.

Hand-fixed:
- `match_same_arms` (forge_notify::is_atx_heading): two arms returning
  `true` collapsed into a single `matches!` pattern.
- `cast_sign_loss` + `format_push_string` (mcp.rs status formatter):
  guarded `i64 → u64` through `u64::try_from(…).unwrap_or(0)` (status
  timestamps are always positive in practice; clamp the skew edge to
  0) and swapped `out.push_str(&format!(…))` for `write!` into the
  buffer with an infallible-writer `let _ =`.
- `doc_lazy_continuation` in turn.rs + manager_server.rs + sh4re/lib.rs:
  doc paragraphs that the markdown parser was treating as list-item
  continuations got either a separating blank line or a `/`-for-`+`
  word swap so the parser stops seeing a list.
- `unused_async` (manager_server::handle_request_schedule_prompt):
  function has no `.await`; dropped the `async` and its `.await` call
  site.
- `needless_pass_by_value` (scheduled_prompts::submit): take
  `&NewSchedule` instead of moving the struct in; updated two prod
  callers and eight test sites to pass references.
- `type_complexity` (approvals::mark_cancelled): hoisted the
  7-tuple SELECT row shape into a `type CancelLookupRow = (…);` alias.

Allow-with-reason for intentional patterns:
- `option_option` (6 sites across dashboard / scheduled_prompts /
  manager_server): `Option<Option<T>>` carries three-state PATCH
  semantics (missing key = leave alone, `Some(None)` = clear,
  `Some(Some(v))` = set). Collapsing to `Option<T>` loses the
  "clear" state.
- `dead_code` (rebuild_queue::QueueKind::Destroy /
  QueueSource::CrashRecover; topology::parent_of / default_seed):
  wire-shape variants + API surfaces kept for the upcoming features
  (#361 follow-ups, future `Destroy` queue routing, crash-recovery
  path). Allowed at the variant / function level with the rationale
  in `reason = "…"`.
- `too_many_lines` on three specific call-sites: a 117-line
  exhaustive-variant test (dashboard_events::kind_tag_matches_…),
  the meta-flake string template renderer
  (meta::render_flake_with_lookup), and the notification poll loop
  (forge_notify::poll_once) — splitting any of them would just hide
  the contiguous shape they exist to keep visible.

`nix flake check` formatting target is still broken on main itself
(pre-existing nixfmt drift across ~28 files unrelated to this PR);
left alone here so the scope stays "crane port + lints the port
exposed" and the operator's review doesn't have to triage drive-by
nixfmt churn.

hive-c0re/src/scheduled_prompts_worker.rs

@@ -32,7 +32,7 @@
 //!    the broker send again, so transient errors self-heal.
 //!  - **one-shots** delete unconditionally after their single
 //!    fan-out pass; a broker failure on a one-shot is NOT
-//!    retried (the operator advisory + last_result are the only
+//!    retried (the operator advisory + `last_result` are the only
 //!    audit trail).
 
 use std::sync::Arc;
@@ -104,7 +104,7 @@ fn tick(coord: &Arc<Coordinator>) {
 }
 
 /// Fan out one schedule's body to every active target. Records
-/// per-target last_result; advances or reaps the parent row at
+/// per-target `last_result`; advances or reaps the parent row at
 /// the end depending on whether `interval_seconds` is set.
 fn fire_schedule(coord: &Arc<Coordinator>, schedule: &Schedule, now: i64) {
     let known: std::collections::HashSet<String> = known_agents(coord);
@@ -118,12 +118,11 @@ fn fire_schedule(coord: &Arc<Coordinator>, schedule: &Schedule, now: i64) {
         // mirrors `to == operator` into its own pane.
         if target != hive_sh4re::OPERATOR_RECIPIENT && !known.contains(target) {
             let reason = format!("no such agent: {target}");
-            if let Err(e) = coord.scheduled_prompts.record_target_result(
-                schedule.id,
-                target,
-                now,
-                &reason,
-            ) {
+            if let Err(e) =
+                coord
+                    .scheduled_prompts
+                    .record_target_result(schedule.id, target, now, &reason)
+            {
                 tracing::warn!(error = ?e, schedule = schedule.id, %target, "record_target_result failed");
             }
             notify_operator_missing_target(coord, schedule, target);
@@ -292,7 +291,11 @@ pub async fn fire_now(
     if schedule.cancelled_at_unix.is_some() {
         anyhow::bail!("schedule {schedule_id} is already cancelled");
     }
-    if !schedule.targets.iter().any(|t| t.cancelled_at_unix.is_none()) {
+    if !schedule
+        .targets
+        .iter()
+        .any(|t| t.cancelled_at_unix.is_none())
+    {
         anyhow::bail!("schedule {schedule_id} has no active targets");
     }
     let known = known_agents_async().await;
@@ -309,12 +312,11 @@ pub async fn fire_now(
         let target = &target_row.target;
         if target != hive_sh4re::OPERATOR_RECIPIENT && !known.contains(target) {
             let reason = format!("manual fire: no such agent: {target}");
-            if let Err(e) = coord.scheduled_prompts.record_target_result(
-                schedule_id,
-                target,
-                now,
-                &reason,
-            ) {
+            if let Err(e) =
+                coord
+                    .scheduled_prompts
+                    .record_target_result(schedule_id, target, now, &reason)
+            {
                 tracing::warn!(error = ?e, schedule = schedule_id, %target, "record_target_result failed");
             }
             notify_operator_missing_target(coord, &schedule, target);