docs: describe the flat container list, not a dormant tree

mara's ruling on the review: documentation describes functionality as
is. The dashboard doc carried a "Topology tree" section marked dormant,
still spelling out the indent lanes, joints and continuation bars the
renderer paints — for a renderer that, with no parent field to walk,
puts every container at depth 0 and emits no prefix column at all. A
section labelled dormant is still a section describing a feature the
code does not have.

Each one now states what the page renders today: SW4RM's C0NTAINERS is
a flat alphabetical list, one row per container, no indent and no glyph;
the tree section says nothing nests and names the code that decides so;
the selection bar lists the bulk actions it has, without a note about
the M0V3 picker it doesn't (agent-hierarchy.md's removal table is where
that record belongs).

Two more the -U15 context sweep turned up outside that section, neither
naming a removed identifier so neither reachable by grep: approvals.md
told an agent to clone "the child's" config repo, and hivectl.md sold
`agent restart` as a way round "the agent hierarchy".

docs/tools/hivectl.md

@@ -163,7 +163,7 @@ raw rows instead of the table.
 
 `agent <name> restart` is the manual equivalent of the MCP `restart`
 tool — useful when you need to kick a container from the host without
-going through the agent hierarchy. For more than one agent at once, use
+going through an agent at all. For more than one agent at once, use
 the top-level `hivectl restart --agents` (or `--agent <name>` repeated) —
 it rides a single DAG and reports per-target failures at the end rather
 than aborting mid-run, instead of shelling out to `agent <name> restart`