feat: add replace subcommand with multi-pattern support

specs/002-add-replace-command/checklists/release.md

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+# Release Readiness Checklist: Replace Command with Multi-Pattern Support
+
+**Purpose**: Verify readiness for release / polish phase  
+**Created**: 2025-10-29  
+**Feature**: [spec.md](../spec.md)
+
+## Documentation
+
+- [x] Quickstart reflects latest syntax and automation workflow
+- [x] CLI reference (`docs/cli-flags.md`) includes replace command usage and warnings
+- [x] AGENTS.md updated with replace command summary
+- [x] CHANGELOG entry drafted for replace command
+
+## Quality Gates
+
+- [x] `go test ./...` passing locally
+- [x] Smoke test script for replace + undo exists and runs
+- [x] Ledger metadata includes pattern counts and is asserted in tests
+- [x] Empty replacement path warns users in preview
+
+## Operational Readiness
+
+- [x] `--dry-run` and `--yes` are mutually exclusive and error when combined
+- [x] Undo command reverses replace operations via ledger entry
+- [x] Scope flags behave identically across list/replace commands
+
+## Notes
+
+- Resolve outstanding checklist items prior to tagging release.

specs/002-add-replace-command/checklists/requirements.md

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+# Specification Quality Checklist: Replace Command with Multi-Pattern Support
+
+**Purpose**: Validate specification completeness and quality before proceeding to planning  
+**Created**: 2025-10-29  
+**Feature**: [spec.md](../spec.md)
+
+## Content Quality
+
+- [x] No implementation details (languages, frameworks, APIs)
+- [x] Focused on user value and business needs
+- [x] Written for non-technical stakeholders
+- [x] All mandatory sections completed
+
+## Requirement Completeness
+
+- [x] No [NEEDS CLARIFICATION] markers remain
+- [x] Requirements are testable and unambiguous
+- [x] Success criteria are measurable
+- [x] Success criteria are technology-agnostic (no implementation details)
+- [x] All acceptance scenarios are defined
+- [x] Edge cases are identified
+- [x] Scope is clearly bounded
+- [x] Dependencies and assumptions identified
+
+## Feature Readiness
+
+- [x] All functional requirements have clear acceptance criteria
+- [x] User scenarios cover primary flows
+- [x] Feature meets measurable outcomes defined in Success Criteria
+- [x] No implementation details leak into specification
+
+## Notes
+
+- Items marked incomplete require spec updates before `/speckit.clarify` or `/speckit.plan`