feat(code): add /code:pr command to generate pull requests (#101)

Add PR generation command that:
- Auto-generates title from branch name
- Creates body with commit list and changed files
- Supports --draft flag for draft PRs
- Supports --reviewer flag to request reviews

Migrated from core-claude PR #46.

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

claude/code/commands/pr.md

@@ -0,0 +1,28 @@
+---
+name: pr
+description: Create a PR with a generated title and description from your commits.
+args: [--draft] [--reviewer @user]
+---
+
+# Create Pull Request
+
+Generates a pull request with a title and body automatically generated from your recent commits.
+
+## Usage
+
+Create a PR:
+`/code:pr`
+
+Create a draft PR:
+`/code:pr --draft`
+
+Request a review:
+`/code:pr --reviewer @username`
+
+## Action
+
+This command will execute the following script:
+
+```bash
+"${CLAUDE_PLUGIN_ROOT}/scripts/generate-pr.sh" "$@"
+```

claude/code/scripts/generate-pr.sh

@@ -0,0 +1,94 @@
+#!/bin/bash
+set -euo pipefail
+
+# Default values
+DRAFT_FLAG=""
+REVIEWERS=""
+
+# Parse arguments
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --draft)
+      DRAFT_FLAG="--draft"
+      shift
+      ;;
+    --reviewer)
+      if [[ -n "$2" ]]; then
+        REVIEWERS="$REVIEWERS --reviewer $2"
+        shift
+        shift
+      else
+        echo "Error: --reviewer flag requires an argument." >&2
+        exit 1
+      fi
+      ;;
+    *)
+      echo "Unknown option: $1" >&2
+      exit 1
+      ;;
+  esac
+done
+
+# --- Git data ---
+# Get default branch (main or master)
+DEFAULT_BRANCH=$(git remote show origin | grep 'HEAD branch' | cut -d' ' -f5)
+if [[ -z "$DEFAULT_BRANCH" ]]; then
+    # Fallback if remote isn't set up or is weird
+    if git show-ref --verify --quiet refs/heads/main; then
+        DEFAULT_BRANCH="main"
+    else
+        DEFAULT_BRANCH="master"
+    fi
+fi
+
+# Get current branch
+CURRENT_BRANCH=$(git rev-parse --abbrev-ref HEAD)
+if [[ "$CURRENT_BRANCH" == "HEAD" ]]; then
+    echo "Error: Not on a branch. Aborting." >&2
+    exit 1
+fi
+
+# Get merge base
+MERGE_BASE=$(git merge-base HEAD "$DEFAULT_BRANCH")
+if [[ -z "$MERGE_BASE" ]]; then
+    echo "Error: Could not find a common ancestor with '$DEFAULT_BRANCH'. Are you up to date?" >&2
+    exit 1
+fi
+
+
+# --- PR Content Generation ---
+
+# Generate Title
+# Convert branch name from kebab-case/snake_case to Title Case
+TITLE=$(echo "$CURRENT_BRANCH" | sed -E 's/^[a-z-]+\///' | sed -e 's/[-_]/ /g' -e 's/\b\(.\)/\u\1/g')
+
+# Get list of commits
+COMMITS=$(git log "$MERGE_BASE"..HEAD --pretty=format:"- %s" --reverse)
+
+# Get list of changed files
+CHANGED_FILES=$(git diff --name-only "$MERGE_BASE"..HEAD)
+
+# --- PR Body ---
+BODY=$(cat <<EOF
+## Summary
+$COMMITS
+
+## Changes
+\`\`\`
+$CHANGED_FILES
+\`\`\`
+
+## Test Plan
+- [ ] TODO
+EOF
+)
+
+# --- Create PR ---
+echo "Generating PR..." >&2
+echo "Title: $TITLE" >&2
+echo "---" >&2
+echo "$BODY" >&2
+echo "---" >&2
+
+# The command to be executed by the plugin runner
+gh pr create --title "$TITLE" --body "$BODY" $DRAFT_FLAG $REVIEWERS