chore(ci,docs): GitHub Actions, ADRs, README overhaul, §21 Hardening Release

- .github/workflows/ci.yml: two jobs — frontend (tsc --noEmit, lint, build,
  Playwright) and backend (Postgres 16 + odoo:19 --test-enable
  --test-tags encoach_api) — catches regressions before merge.
- docs/adr/: start an Architecture Decision Record trail with
  0001 canonical directory layout, 0002 JWT refresh flow,
  0003 paginated response envelope, 0004 RAG metadata + chunking.
- docs/PROJECT_SUMMARY.md §21 Hardening Release: full recap of the AI
  quality loop, compliance, Paymob, i18n, and CI work shipped in this
  drop, plus new DB tables, REST routes, frontend routes, verification
  results, and operator-facing configuration.
- README.md refreshed for the v4 split-repo doctrine and the new feature
  surface.
- new_project/DEPRECATED.md: formal retirement notice pointing at
  backend/ as the canonical tree.

Made-with: Cursor

docs/adr/README.md

@@ -0,0 +1,22 @@
+# Architecture Decision Records
+
+This folder contains lightweight ADRs documenting significant architectural
+decisions made on the EnCoach platform. Each ADR is numbered, dated, and
+immutable once "Accepted" — if a decision is revisited, open a new ADR that
+supersedes the old one instead of rewriting history.
+
+## Index
+
+| # | Title | Status |
+|---|-------|--------|
+| [0001](0001-canonical-directory-layout.md) | Canonical `backend/` and `frontend/` directory layout | Accepted |
+| [0002](0002-jwt-refresh-token-flow.md) | JWT access + refresh tokens with revocation ledger | Accepted |
+| [0003](0003-paginated-response-envelope.md) | Canonical paginated response envelope | Accepted |
+| [0004](0004-rag-metadata-and-chunking.md) | RAG metadata + chunking for vector store | Accepted |
+
+## Writing a new ADR
+
+1. Copy [`0000-template.md`](0000-template.md) to the next number.
+2. Fill in **Context**, **Decision**, **Consequences**.
+3. Keep it short (1 page). Link to source files or PRs for detail.
+4. Update the index above and open a PR.