feat(#2485): remove vestigial Noop + StartupSweep residuals

Since the boot sweep (#2450) and meta-update cascade (#2476) became
single DAGs that grow subgraphs in-place, nothing constructs the old
fan-out anchors/parents anymore:

- NodeKind::Noop (the old boot_root grouping anchor) — no constructors.
- Template::StartupSweep / Source::StartupSweep (the old fan-out parent
  template + cascade-child source) — replaced by Template::Boot and
  Source::AutoUpdate/MetaUpdate respectively.

Drops the three variants + their as_str arms + the Noop executor arm, and
refreshes the stale fan-out/anchor doc comments (Boot/MetaUpdate/Source
docs, coordinator.md, dashboard.md). Frontend: the queue-kind glyph moves
from the dead startup_sweep to boot (which had none), and the dead
rqe-source-startup_sweep style is dropped.

No behaviour change — pure dead-variant removal.

hive-c0re/src/job_queue/exec.rs

@@ -98,9 +98,6 @@ pub(super) async fn run_node(coord: &Arc<Coordinator>, claim: &Claim) -> Result<
         NodeKind::WriteDropin => run_write_dropin(coord, claim).await,
         NodeKind::WritePermFile => run_write_perm_file(coord, claim, &ctx).await,
         NodeKind::ApprovalDeploy => run_approval_deploy(coord, claim).await,
-        // A pure grouping anchor (boot root): no work, completes immediately so
-        // its child DAGs settle it and the boot tree resolves.
-        NodeKind::Noop => Ok(NodeOutput::default()),
         NodeKind::SetWanted { up } => run_set_wanted(coord, claim, *up),
     }
 }

hive-c0re/src/job_queue/model.rs

@@ -115,11 +115,6 @@ pub enum NodeKind {
     /// deploy stays inside `actions.rs` in v1 — deliberately not
     /// modeled as scheduler nodes (see the design doc §9).
     ApprovalDeploy,
-    /// No-op anchor that completes immediately with no work. Vestigial since
-    /// the boot sweep became one in-DAG graph (no `boot_root` anchor / child
-    /// DAGs) — slated for removal with the other `StartupSweep` residuals.
-    /// Holds no lease and no build slot.
-    Noop,
     /// Write the agent's durable power intent (`wanted = Up` when `up`, else
     /// `Offline`) as a first-class DAG node, at the head of a power-op
     /// template so the downstream `Reconcile` reads it. Replaces the old
@@ -154,7 +149,6 @@ impl NodeKind {
             NodeKind::WriteDropin => "write_dropin",
             NodeKind::WritePermFile => "write_perm_file",
             NodeKind::ApprovalDeploy => "approval_deploy",
-            NodeKind::Noop => "noop",
             NodeKind::SetWanted { .. } => "set_wanted",
         }
     }

hive-c0re/src/job_queue/templates.rs

@@ -210,11 +210,10 @@ pub fn meta_update(
     }
 }
 
-// The boot is now assembled inline in `workers/auto_update.rs::submit_boot_tree`
-// as ONE DAG (a sweep `MetaLock` root that grows rebuild subgraphs in-DAG, plus
-// a `Reconcile` root per drifted agent) — no `boot_root` Noop anchor, no
-// `startup_sweep` parent template, no per-agent child DAGs. The old single-use
-// `boot_root` / `startup_sweep` builders were inlined there and removed.
+// The boot is assembled inline in `workers/auto_update.rs::submit_boot_tree`
+// as ONE `Boot` DAG (a sweep `MetaLock` root that grows rebuild subgraphs
+// in-DAG, plus a `Reconcile` root per drifted agent) — no anchor node and no
+// per-agent child DAGs.
 
 /// Validate a spec before it enters the queue: node ids are dense
 /// (index = id), deps reference existing nodes, and the dep graph is