chore: bootstrap project (sprint 0)

Lay down the project foundation before Sprint 1 implementation:

- SPEC.md enriched with a "Décisions techniques" section that pins
  down 3-role auth (admin super-user / redteam / soc), JWT bearer,
  single-container Flask+React topology, minimal Engagement model,
  local MITRE STIX bundle, and the Makefile target list.
- .claude/agents/ defines the 6 sub-agents per SPEC.md § Team:
  backend-builder, frontend-builder, spec-reviewer (project override
  covering plan-vs-spec + code-vs-spec), code-reviewer, test-verifier,
  devil-advocate.
- tasks/todo.md holds the full Sprint 1 plan (Auth + CRUD Engagement)
  validated by spec-reviewer on 2026-05-26 after one round of fixes.
- CHANGELOG.md and tasks/lessons.md scaffolded.
- .gitignore covers Python, Node, Playwright, secrets, build artifacts
  and Claude Code worktrees.

No application code is shipped in this commit — Sprint 1 will be a
separate branch and PR.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -0,0 +1,19 @@
+# Changelog
+
+All notable changes to Mimic are tracked here.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/) and this project adheres to [Semantic Versioning](https://semver.org/).
+
+## [Unreleased]
+
+### Added
+- Initial `SPEC.md` covering project scope, simulation model, workflow, stack, and agent team.
+- Technical decisions section in `SPEC.md`: 3-role auth (admin/redteam/soc), JWT Bearer, single-container Flask+React, local MITRE STIX bundle, minimal Engagement model, admin bootstrap via Makefile target.
+- Sub-agent definitions under `.claude/agents/` for backend-builder, frontend-builder, spec-reviewer (project override of the built-in, covers plan-vs-spec and code-vs-spec), code-reviewer, test-verifier, devil-advocate.
+- Project tracking scaffold: `tasks/todo.md`, `tasks/lessons.md`, `CHANGELOG.md`, `.gitignore`.
+
+### Changed
+- 2026-05-26 — `admin` role widened in `SPEC.md` § Décisions techniques. The initial draft restricted admin to user-management only; after the Sprint 1 plan review surfaced the operational pain (admin would need a second `redteam` account just to manage engagements), the user decided to make admin a super-user that cumulates redteam rights on engagements/simulations.
+
+### Removed
+- _none_