feat: clean install (Gitea en dur, scan off) + durcissement sécurité entreprise

Gitea
- lien « Code source » hardcodé (REPO_SOURCE_URL) vers le dépôt, toujours visible
- retrait complet du réglage configurable (api.ts, route+store settings, SettingsView, i18n, help, tests)

Découverte des dépôts
- aucune racine de scan par défaut → pas de scan au premier démarrage (clean install)
- corrige la découverte des dépôts à l'INTÉRIEUR d'une racine qui est elle-même un repo
  (depth 0 = conteneur de scan, on descend ; depth > 0 = feuille)

Sécurité « enterprise-deployable »
- en-têtes HTTP durcis (CSP, X-Frame-Options, nosniff, Referrer-Policy, HSTS conditionnel, no-store API), header Server retiré
- permissions DB 0o600 / dossier de données 0o700 ; error handler sanitisé ; garde Content-Type sur les mutations
- chiffrement au repos AES-256-GCM des secrets (server_secret, clé privée VAPID) via SecretBox
- journal d'audit (migration #7) + endpoint /audit-logs + RGPD export/effacement + UI Réglages
- SECURITY.md, docs/ENTERPRISE_DEPLOYMENT.md, sections README EN/FR, SBOM CycloneDX en CI

CI
- pack-smoke packe depuis le contexte du package (cd packages/server) au lieu de « npm pack -w » :
  corrige l'embarquement de @arboretum/shared dans le tarball

Purge des données personnelles du dépôt public
- suppression de spikes/s4-discovery/result.json, reformulation du VERDICT
- chemin de test générique, anonymisation des 5 fixtures de dialogues

SECURITY.md

@@ -0,0 +1,61 @@
+# Security Policy
+
+Arboretum is a self-hosted daemon that serves a web dashboard to drive git worktrees and the
+Claude Code sessions running on them. **A web terminal is remote code execution by design** — that
+is the product, not a bug. Arboretum's security model is therefore built on *structural* guards
+(loopback-only binding, authenticated access, strict Origin checks) far more than on cryptography
+alone.
+
+This document describes the threat model, the controls that are implemented, the deliberate
+trade-offs, and how to report a vulnerability. For hardening a deployment in a regulated
+environment, see [`docs/ENTERPRISE_DEPLOYMENT.md`](docs/ENTERPRISE_DEPLOYMENT.md).
+
+## Threat model
+
+- **Single-user by design.** Arboretum runs on the owner's machine and is meant for one operator.
+  There is no multi-tenant isolation and no RBAC — and none is claimed.
+- **Loopback by default.** The server binds `127.0.0.1`; `config.ts` *refuses* any non-loopback bind
+  unless you pass `--i-know-this-exposes-a-terminal`. Remote access is expected via **Tailscale Serve**
+  (TLS + tailnet identity), never by opening a port.
+- **The terminal is RCE.** Anyone who can authenticate can run code. The controls below exist to make
+  sure only the authenticated operator reaches it, and that the surrounding surface (cookies, headers,
+  data at rest) is hardened.
+
+## Implemented controls
+
+| Area | Control | Where |
+| --- | --- | --- |
+| Network | Loopback-only default; non-loopback refused without explicit flag | `packages/server/src/config.ts` |
+| AuthN | Global guard on **all** `/api/**` and `/ws` (only login is public, and rate-limited) | `packages/server/src/app.ts` |
+| AuthN | Tokens stored **hashed** (SHA-256), compared in constant time; bootstrap token shown once | `packages/server/src/auth/service.ts` |
+| Sessions | Cookie is an HMAC-SHA256 signed payload, `HttpOnly` + `SameSite=Strict`, `Secure` when HTTPS | `packages/server/src/routes/auth.ts` |
+| CSRF / WS | Strict `Origin` check on every `/api/**` and `/ws` request (anti cross-site WS hijacking) | `packages/server/src/app.ts` |
+| CSRF | Mutations carrying a body must be `application/json` | `packages/server/src/app.ts` |
+| Rate limit | Global login rate limit with exponential backoff (not per-IP — Tailscale fronts everything as 127.0.0.1) | `packages/server/src/auth/service.ts` |
+| HTTP headers | CSP, `X-Frame-Options: DENY`, `X-Content-Type-Options: nosniff`, `Referrer-Policy`, `Permissions-Policy`, conditional HSTS, `Cache-Control: no-store` on API; `Server` header stripped | `packages/server/src/app.ts` |
+| Injection | All SQL is parameterized; all git calls use `execFile` (no shell); path-traversal guards | `packages/server/src/**` |
+| Data at rest | DB file/dir forced to `0o600`/`0o700`; sensitive secrets (server secret, VAPID private key) encrypted with AES-256-GCM | `packages/server/src/db/index.ts`, `core/secret-box.ts` |
+| Audit | Persistent audit log of sensitive mutations (tokens, settings, secrets, push, groups) | `packages/server/src/core/audit-log.ts` |
+| Privacy | GDPR export (`/api/v1/data/export`) and erasure (`/api/v1/data/delete-my-data`) | `packages/server/src/routes/data.ts` |
+| Install | Runs as a **user** service (systemd user unit / launchd LaunchAgent), never root | `packages/server/src/cli/install.ts` |
+
+## Deliberate trade-offs
+
+- **Long-lived API tokens.** Tokens do not expire by age (CLI automation stability) but can be revoked
+  instantly, and `last_used_at` is tracked. Review and rotate tokens periodically.
+- **Encryption-at-rest key management.** With no `ARBORETUM_SECRET_KEY` set, the encryption key lives in
+  `dataDir/secret.key` (`0o600`) next to the database — this protects a leaked database *copy* (backup,
+  WAL) but not a full `dataDir` compromise. For strong protection, set `ARBORETUM_SECRET_KEY` and store it
+  separately from database backups. Full-DB SQLCipher is intentionally avoided (it breaks the `npx`
+  prebuilt portability).
+- **No multi-user model.** If you need multiple operators with isolation, Arboretum is not the right tool.
+
+## Reporting a vulnerability
+
+Please report security issues **privately** — do not open a public issue.
+
+- Email: **security@johanleroy.fr** (or `contact@johanleroy.fr`).
+- Include a description, affected version, and reproduction steps.
+- Expect an acknowledgement within **7 days** and a coordinated disclosure window of up to **90 days**.
+
+Thank you for helping keep Arboretum users safe.