Add /pr slash command to automate pull request creation (#10)

Standardizes PR creation so contributors run the same CI checks (tsc,
biome, jest) locally before pushing, auto-detect issue numbers from
branch names for closing references, and enable squash automerge by
default.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: dfalling

.claude/commands/pr.md

@@ -0,0 +1,75 @@
+---
+description: Create a pull request — runs precommit, commits any changes, detects issue numbers in branch names, and enables automerge by default.
+allowed-tools: Bash, Read, Edit, Write, Glob, Grep
+---
+
+## Context
+
+- Current branch: !`git branch --show-current`
+- Git status: !`git status --short`
+- Git diff (staged + unstaged): !`git diff HEAD`
+- Recent commits: !`git log --oneline -5`
+
+## Your task
+
+Arguments (optional PR title or extra instructions): $ARGUMENTS
+
+Follow these steps in order:
+
+### Step 1 — Run pre-PR checks and fix issues
+
+This project has no single precommit command. Run the same checks CI enforces, in order, and fix any errors or warnings before proceeding. Repeat each until it passes cleanly:
+
+1. TypeScript: `bunx tsc --noEmit`
+2. Biome (lint + format): `bun run lint` — use `bun run lint:fix` to auto-fix where possible
+3. Tests: `bun run test -- --ci`
+
+If you changed any GraphQL operations or the schema, also run `bun run codegen` and include the regenerated files.
+
+### Step 2 — Commit any uncommitted changes
+
+If there are staged or unstaged changes after precommit passes:
+1. Stage all changed tracked files: `git add -u`
+2. Draft a concise commit message that describes the changes (focus on "why", not "what")
+3. Create the commit
+
+### Step 3 — Push the branch
+
+Push the current branch to origin:
+```
+git push -u origin HEAD
+```
+
+### Step 4 — Determine PR description
+
+Check the current branch name for a GitHub issue number pattern (e.g. `123-fix-something`, `feature/456-add-widget`, `fix-789`).
+
+- If an issue number is found, append `Closes #<number>` to the PR body.
+- If no issue number is found, omit the closing reference.
+
+### Step 5 — Create the pull request
+
+Use `gh pr create` with:
+- Title: derived from $ARGUMENTS if provided, otherwise infer from the commit messages on the branch vs main
+- Body: brief summary of changes, plus `Closes #<number>` if applicable (use a HEREDOC to pass the body)
+- Base branch: `main`
+
+Example:
+```bash
+gh pr create --base main --title "..." --body "$(cat <<'EOF'
+## Summary
+- <bullet points>
+
+Closes #<number>
+EOF
+)"
+```
+
+### Step 6 — Enable automerge
+
+Unless $ARGUMENTS contains "no-automerge" or "no automerge", enable automerge after the PR is created:
+```bash
+gh pr merge --auto --squash
+```
+
+If the repo does not support automerge (command fails), note this to the user but do not treat it as a fatal error.