Add GitHub issue pipelines and prompts using gh CLI

gh-issue-impl, gh-issue-research, gh-issue-rewrite, gh-issue-update
pipelines with corresponding prompts for fetch-assess, plan,
implement, and create-pr steps.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.wave/prompts/github-issue-impl/implement.md

@@ -0,0 +1,87 @@
+You are implementing a GitHub issue according to the plan and task breakdown.
+
+Input: {{ input }}
+
+## Working Directory
+
+You are running in an **isolated git worktree** shared with previous pipeline steps.
+Your working directory IS the project root. The feature branch was created by the
+plan step and is already checked out. All git operations here are isolated from
+the main working tree.
+
+## Instructions
+
+### Step 1: Load Context
+
+1. Get the issue details and branch name from the issue assessment artifact
+2. Get the task breakdown, file changes, and feature directory from the plan artifact
+
+### Step 2: Read Plan Files
+
+Navigate to the feature directory and read:
+- `spec.md` — the full specification
+- `plan.md` — the implementation plan
+- `tasks.md` — the phased task breakdown
+
+### Step 3: Execute Implementation
+
+Follow the task breakdown phase by phase:
+
+**Setup first**: Initialize project structure, dependencies, configuration
+
+**Tests before code (TDD)**:
+- Write tests that define expected behavior
+- Run tests to confirm they fail for the right reason
+- Implement the code to make tests pass
+
+**Core development**: Implement the changes specified in the plan
+
+**Integration**: Wire components together, update imports, middleware
+
+**Polish**: Edge cases, error handling, documentation updates
+
+### Step 4: Validate Between Phases
+
+After each phase, run:
+```bash
+go test -race ./...
+```
+
+If tests fail, fix the issue before proceeding to the next phase.
+
+### Step 5: Mark Completed Tasks
+
+As you complete each task, mark it as `[X]` in `tasks.md`.
+
+### Step 6: Final Validation
+
+After all tasks are complete:
+1. Run `go test -race ./...` one final time
+2. Verify all tasks in `tasks.md` are marked complete
+3. Stage and commit all changes:
+   ```bash
+   git add -A
+   git reset HEAD -- .wave/artifacts .wave/output .claude CLAUDE.md 2>/dev/null || true
+   git commit -m "feat: implement #<ISSUE_NUMBER> — <short description>"
+   ```
+
+Commit changes to the worktree branch.
+
+## Agent Usage — USE UP TO 6 AGENTS
+
+Maximize parallelism with up to 6 Task agents for independent work:
+- Agents 1-2: Setup and foundational tasks (Phase 1-2)
+- Agents 3-4: Core implementation tasks (parallelizable [P] tasks)
+- Agent 5: Test writing and validation
+- Agent 6: Integration and polish tasks
+
+Coordinate agents to respect task dependencies:
+- Sequential tasks (no [P] marker) must complete before dependents start
+- Parallel tasks [P] affecting different files can run simultaneously
+- Run test validation between phases
+
+## Error Handling
+
+- If a task fails, halt dependent tasks but continue independent ones
+- Provide clear error context for debugging
+- If tests fail, fix the issue before proceeding to the next phase