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/speckit-flow/plan.md

@@ -0,0 +1,41 @@
+You are creating an implementation plan for a feature specification.
+
+Feature context: {{ 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 a
+previous step and is already checked out.
+
+## Instructions
+
+Follow the `/speckit.plan` workflow:
+
+1. Find the feature directory and spec file path from the spec info artifact
+2. Run `.specify/scripts/bash/setup-plan.sh --json` to get FEATURE_SPEC, IMPL_PLAN,
+   SPECS_DIR, and BRANCH paths
+3. Load the feature spec and `.specify/memory/constitution.md`
+4. Follow the plan template phases:
+
+   **Phase 0 — Outline & Research**:
+   - Extract unknowns from the spec (NEEDS CLARIFICATION markers, tech decisions)
+   - Research best practices for each technology choice
+   - Consolidate findings into `research.md` with Decision/Rationale/Alternatives
+
+   **Phase 1 — Design & Contracts**:
+   - Extract entities from spec → write `data-model.md`
+   - Generate API contracts from functional requirements → `/contracts/`
+   - Run `.specify/scripts/bash/update-agent-context.sh claude`
+
+5. Evaluate constitution compliance at each phase gate
+6. Stop after Phase 1 — report branch, plan path, and generated artifacts
+
+## CONSTRAINTS
+
+- Do NOT spawn Task subagents — work directly in the main context
+- Do NOT use WebSearch — all information is in the spec and codebase
+
+## Output
+
+Produce a JSON status report matching the injected output schema.