Merge main into dev: back-merge wiki dev-env updates before the 3.1.0 release

# Conflicts:
#	wiki/Development-environment.md

wiki/Development-environment.md

@@ -154,6 +154,36 @@ The `@trek/shared` package is the single source of truth for code shared between
 | `npm run lint`              | Lint source                          |
 | `npm run format`            | Format source                        |
 
+### Root (`/`)
+
+These commands run across all workspaces at once and are the recommended way to work:
+
+| Command              | Description                                                         |
+|----------------------|---------------------------------------------------------------------|
+| `npm run dev`        | Build shared, then start shared (watch), server, and client together via `concurrently` |
+| `npm run build`      | Build shared → server → client in order                            |
+| `npm test`           | Run tests in shared, server, and client                            |
+| `npm run test:cov`   | Run coverage for server and client                                 |
+| `npm run test:e2e`   | Run end-to-end tests (server)                                      |
+| `npm run lint`       | Lint shared, server, and client                                    |
+| `npm run format`     | Format shared, server, and client                                  |
+| `npm run format:check` | Check formatting across all workspaces                           |
+
+### Shared (`/shared`)
+
+The `@trek/shared` package is the single source of truth for code shared between the client and server. It currently holds **Zod schemas that define API contracts** (request/response shapes, common primitives, pagination). Both workspaces import from it so schema changes automatically propagate to both sides.
+
+> **Upcoming:** the i18n translation layer will be migrated into this package so that translation keys and types are enforced across the stack from one place.
+
+| Command                | Description                        |
+|------------------------|------------------------------------|
+| `npm run build`        | Compile shared package (tsup)      |
+| `npm run build:watch`  | Compile in watch mode              |
+| `npm test`             | Run tests                          |
+| `npm run typecheck`    | Type-check without emitting        |
+| `npm run lint`         | Lint source                        |
+| `npm run format`       | Format source                      |
+
 ### Server (`/server`)
 
 | Command                    | Description                              |