fix(ci): clear the agent-skills-sync base-red on release/v3.8.51

check:agent-skills-sync exits 2 on the clean tip (reproduced in a throwaway
probe worktree cut from origin/release/v3.8.51, with none of this branch's
commits): the generator wants to rewrite skills/cli-tunnel/SKILL.md.

Cause: #13009 ('read positionals declared with .addArgument()') taught the
generator to surface positional arguments, so the committed skill's
'tunnel create' heading and example went stale against 'tunnel create [type]'.

Regenerated with the official generator (scripts/skills/generate-agent-skills.mjs
--apply), never hand-edited. The gate now exits 0.

Refs #12732

changelog.d/maintenance/0000-basered-agent-skills-cli-tunnel.md

@@ -0,0 +1 @@
+- Clear the `release/v3.8.51` `check:agent-skills-sync` base-red: regenerate `skills/cli-tunnel/SKILL.md` so the `tunnel create [type]` positional that #13009 taught the generator to read is reflected in the committed skill.

skills/cli-tunnel/SKILL.md

@@ -37,12 +37,12 @@ omniroute tunnel
 omniroute tunnel list
 ```
 
-### `tunnel create`
+### `tunnel create [type]`
 
 **Example:**
 
 ```bash
-omniroute tunnel create
+omniroute tunnel create [type]
 ```
 
 ### `tunnel stop <type>`