docs(adr): convert all ADRs to MADR 2.1.2 format

Rewrites all 7 backend ADRs from a custom structure to the MADR 2.1.2
template required by the VS Code ADR Manager extension: bullet metadata
(Status/Date), standardised section headings, "Chosen option: X, because Y"
wording, and explicit Pros/Cons blocks per option.

docs/decisions/0004-route-organisation-by-domain.md

@@ -1,22 +1,46 @@
-# ADR 0004: Route Organisation by Functional Domain
+# Organise routes by functional domain
 
-**Date:** 2026-04-26
-**Status:** Accepted
+* Status: accepted
+* Date: 2026-04-26
 
-## Context
+## Context and Problem Statement
 
-The API covers four independent functional domains (skydive, cms, ecommerce, herowars), each with distinct models, business logic, and frontend consumers. A flat route structure would make it difficult to reason about domain boundaries and onboard new contributors.
+The API covers four independent functional domains (skydive, cms, ecommerce, herowars), each with distinct models, business logic, and frontend consumers. How should routes be organised to reflect these boundaries?
 
-## Decision
+## Considered Options
 
-Routes are grouped under `src/routes/api/<domain>/` with a barrel index (`src/routes/api/index.js`). Each domain owns its routes, controllers, services, and models independently. The domain prefix is reflected in the API path (e.g. `/api/skydive/jumps`, `/api/cms/articles`).
+* Domain-based organisation (`src/routes/api/<domain>/`)
+* Flat structure (all routes at one level)
 
-This structure mirrors the frontend's domain organisation (see frontend ADR 0011), making the full-stack data flow traceable: a frontend service under `core/services/skydive/` calls `/skydive/` routes, which map to `src/routes/api/skydive/`.
+## Decision Outcome
 
-Legacy `v1/`, `v2/`, `v3/` directories exist alongside the active routes as backup snapshots from earlier iterations. They are slated for removal once their contents are confirmed no longer needed (see ADR 0007).
+Chosen option: "Domain-based organisation", because it makes domain boundaries explicit and mirrors the frontend's service structure, making the full-stack data flow traceable.
 
-## Consequences
+Routes are grouped under `src/routes/api/<domain>/` with a barrel index (`src/routes/api/index.js`). The domain prefix is reflected in the API path (e.g. `/api/skydive/jumps`, `/api/cms/articles`). Each domain owns its routes, controllers, services, and models independently. This structure mirrors the frontend's domain organisation (see frontend ADR 0011).
 
-- **Positive:** Domain boundaries are explicit and enforced by directory structure.
-- **Positive:** Consistent mapping between frontend service paths and backend routes simplifies debugging.
-- **Negative:** Cross-domain features (shared auth middleware, user model) live in `src/middlewares/` and `src/database/models/` respectively, outside any domain folder.
+### Positive Consequences
+
+* Domain boundaries are explicit and enforced by directory structure.
+* Consistent mapping between frontend service paths and backend routes simplifies debugging — a frontend service under `core/services/skydive/` maps to `src/routes/api/skydive/`.
+
+### Negative Consequences
+
+* Cross-domain features (shared auth middleware, user model) live in `src/middlewares/` and `src/database/models/` respectively, outside any domain folder.
+
+## Pros and Cons of the Options
+
+### Domain-based organisation
+
+* Good, because each domain is self-contained and independently navigable.
+* Good, because symmetric with the frontend service structure.
+* Bad, because shared concerns need a neutral layer outside domain folders.
+
+### Flat structure
+
+* Good, because simpler for very small APIs.
+* Bad, because domain boundaries become invisible as the API grows.
+
+## Links
+
+* Legacy `v1/`, `v2/`, `v3/` directories exist alongside `api/` as backup snapshots from earlier iterations — see [ADR 0007](0007-legacy-routes-removal.md) for their planned removal.
+* Related to frontend [ADR 0011](../../adastra_app/docs/decisions/0011-feature-domain-organisation.md)