ci(fix-issue): Register skill in agents.toml for dotagents tracking

A reviewer flagged the unregistered skill as a discovery bug — that
claim is wrong (`.claude/skills` is a directory-level symlink to
`.agents/skills`, so all skills under there resolve regardless of
`agents.toml` registration), but the registration is still worth doing:

- `agents.lock` only contains integrity hashes for registered skills;
  unregistered ones are invisible to `dotagents install` verification.
- Every other in-repo skill (`triage-issue`, `release`, etc.) uses
  `source = "path:.agents/skills/<name>"` — inconsistent omission.
- If `dotagents` ever adds destructive sync behavior, unregistered
  skills are at risk.

Not touching `agents.lock` — the next `dotagents install` run regenerates
it with the computed integrity hash.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: mydea

agents.toml

@@ -26,6 +26,10 @@ source = "path:.agents/skills/add-cdn-bundle"
 name = "e2e"
 source = "path:.agents/skills/e2e"
 
+[[skills]]
+name = "fix-issue"
+source = "path:.agents/skills/fix-issue"
+
 [[skills]]
 name = "fix-security-vulnerability"
 source = "path:.agents/skills/fix-security-vulnerability"