fix(skills): collapse verb-enumerated descriptions to one capability clause

An independent audit of the ADR-0020 retrofit (issue #99) found that
git-submodules, git-worktrees, and gitea-files each collapsed their
description length correctly during retrofit but left the capability
clause as a verb enumeration (e.g. "Create, list, lock, move, remove,
prune, or repair") instead of ADR-0020's required single clause. The
deterministic char-count gate can't catch this — it's a qualitative
rubric violation the retrofit commits' own messages never claimed to
address, only measurable length/word-count fixes.

Validated clean via skill-audit and skill-size-check after the fix;
boundary clauses and routing targets left untouched.

Refs #99

plugins/git/.apm/skills/git-submodules/SKILL.md

@@ -2,8 +2,8 @@
 name: git-submodules
 
 description: >
-  Use when managing Git submodules — adding, updating, pinning, inspecting,
-  repointing, or removing a nested repository inside a superproject.
+  Use when managing Git submodules — the full lifecycle of a nested
+  repository inside a superproject.
   Not multiple checkouts of one repo -> `git-worktrees`.
   Not the superproject's own remotes -> `git-remotes`.