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/0007-legacy-routes-removal.md

@@ -1,25 +1,52 @@
-# ADR 0007: Removal of Legacy Route Directories (v1, v2, v3)
+# Remove legacy route directories v1, v2, v3
 
-**Date:** 2026-04-26
-**Status:** Proposed
+* Status: proposed
+* Date: 2026-04-26
 
-## Context
+## Context and Problem Statement
 
-The `src/routes/` directory contains three legacy subdirectories (`v1/`, `v2/`, `v3/`) alongside the active `api/` directory. These are backup snapshots of earlier API iterations, kept during the migration to the current domain-based structure. They are not mounted in the application and serve no runtime purpose.
+The `src/routes/` directory contains three legacy subdirectories (`v1/`, `v2/`, `v3/`) alongside the active `api/` directory. These are backup snapshots of earlier API iterations kept during the migration to the current domain-based structure. They are not mounted in the application. Should they be removed?
 
-Their presence:
-- Creates confusion about which routes are active.
-- Adds noise to `grep` and IDE navigation.
-- Risks accidentally referencing stale logic.
+## Decision Drivers
 
-## Decision
+* Legacy directories create confusion about which routes are active.
+* They add noise to `grep` output and IDE navigation.
+* Stale logic risks being accidentally referenced.
 
-Remove `v1/`, `v2/`, and `v3/` directories once the following is confirmed:
-- No active code references them (direct imports or dynamic requires).
-- Their content has been superseded by the equivalent routes under `src/routes/api/`.
+## Considered Options
 
-## Consequences
+* Remove `v1/`, `v2/`, `v3/` after verification
+* Keep them indefinitely
 
-- **Positive:** Cleaner repository. Only active routes remain.
-- **Risk:** If any code path still references these directories, removal would cause a runtime error. Verify with `grep -r "routes/v[123]"` before deleting.
-- **Status rationale:** Marked as *Proposed* rather than *Accepted* until the verification step is completed and the deletion is committed.
+## Decision Outcome
+
+Chosen option: "Remove after verification", because the directories serve no runtime purpose and their presence actively harms codebase clarity.
+
+Before deletion, verify: no active code references them (direct imports or dynamic requires) and their content has been superseded by the equivalent routes under `src/routes/api/`. Verification command: `grep -r "routes/v[123]" src/`.
+
+This ADR is marked *proposed* rather than *accepted* until the verification step is completed and the deletion is committed.
+
+### Positive Consequences
+
+* Cleaner repository — only active routes remain visible.
+* Eliminates the risk of accidentally referencing stale logic.
+
+### Negative Consequences
+
+* If any code path still references these directories, removal would cause a runtime error. The verification step mitigates this risk.
+
+## Pros and Cons of the Options
+
+### Remove after verification
+
+* Good, because removes dead code that harms navigability.
+* Bad, because irreversible without git history — must verify before deleting.
+
+### Keep indefinitely
+
+* Good, because no risk of breakage.
+* Bad, because perpetuates confusion about what is active.
+
+## Links
+
+* Related to [ADR 0004](0004-route-organisation-by-domain.md) — domain-based `api/` structure that replaces these legacy directories.