fix(skills): make git-workflow script paths portable

All four git-feature-* skills hardcoded /Users/torcsi/dev/kicad-wasm/ for
the helper-script invocations and one documentation example. That path
only resolved on the original author's machine — anyone else picking up
/git-feature-{start,commit,sync,finish} would hit "No such file or
directory" before the first pre-flight check ran.

Replaces the absolute paths with relative ones (`bash scripts/...`) and
rewrites the rebase-conflict handoff message in git-feature-sync.md to use
`git -C kicad ...` style instead of a hardcoded cd.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

scripts/git-workflow/repos.sh

@@ -2,7 +2,7 @@
 # Sourced library. Single source of truth for the 3-repo layout.
 # Usage: source "$(dirname "$0")/repos.sh"
 
-ROOT_DIR="/Users/torcsi/dev/kicad-wasm"
+ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
 
 REPOS=(root kicad wxwidgets)