claude-plugins: format the swarm-logs skill with nix fmt

treefmt normalises markdown emphasis to underscores; the file was
written with asterisks and never run through `nix fmt`. Also ends the
sentence before the scoping note with a full stop rather than a colon,
since a paragraph now sits between it and the example block.

Refs #4460

claude-plugins/plugins/base/skills/swarm-logs/SKILL.md

@@ -38,7 +38,7 @@ one, so a bare word matches across every hive in the swarm." There's no
 per-hive flag to fix this from the CLI side — scope it in the query
 string instead. The collector tags every log line with `_HOSTNAME`,
 `_MACHINE_ID`, and `_SYSTEMD_UNIT` as stream fields, so add one of those
-to a query you want confined to your own machine or service:
+to a query you want confined to your own machine or service.
 
 Reach for `_MACHINE_ID` rather than `_HOSTNAME` when you mean one
 machine. A hostname is a configuration value, so two machines can carry
@@ -80,7 +80,7 @@ tooling or auth problem to fix, not a log finding to report.
 
 ## Before you believe an empty result, run a control
 
-An empty result *looks* like proof of absence, but it's just as
+An empty result _looks_ like proof of absence, but it's just as
 consistent with a `_time:` window that missed the event, a scoping field
 that doesn't match what you expected, or a typo in the search term. Before
 reporting "no matching logs," run a second query you know must return