feat(styles,react): stretch grid slot content to its cell

[Gnuk]

Closes #21

A ippon-grid--slot already takes the full height of its row, but it carried nothing but its column span. With no display of its own it stayed a block box, so its child kept height: auto and cards of a same row ended at different heights.

Fix

Opt-in alternative on the slot, so nothing changes for current users:

.ippon-grid--slot.-stretch {
  display: grid;
}

The slot becomes a grid container, so its child stretches by default whatever that child is (ippon-card, ippon-button-card, …) — no per-component -full-height alternative needed.

It surfaces as a stretch prop on IpponGridSlot.

Measured

Three-column row, cards with unequal content, 1440px viewport:

	slot	card
without -stretch	70px / 70px / 70px	52px / 70px / 52px
with -stretch	70px / 70px / 70px	70px / 70px / 70px

Also in this branch

The pick-issue-to-pr skill now works in the current checkout instead of a git worktree, and starts from the branch already checked out:

• a branch already linked to an issue — by an open PR referencing it, or by an issue number in its name — picks that issue, with no list and no question;
• a branch is created only when the checkout sits on the default branch, so the step is often a no-op.

It also describes its GitHub operations by intent, so either a GitHub MCP server or the gh CLI can serve them.

Its companion cleanup-workspaces only pruned the ~/.workspace worktrees the old flow created, so it is removed along with them.

🤖 Generated with Claude Code

https://claude.ai/code/session_01FdUKMJAAhX2MwvTbw1Uxan