Add Prettier and ESLint tooling (Refs #77)

docs/development/README.md

@@ -10,7 +10,7 @@ does not require a Docker socket or direct access to host filesystems.
 
 ## Run locally
 
-Use Node.js 22.12+ (the container uses Node.js 22), npm and Python 3.
+Use Node.js 22.13+ (the container uses Node.js 22), npm and Python 3.
 
 ```sh
 npm ci
@@ -76,12 +76,27 @@ remove the generated fixture directory.
 ## Checks and builds
 
 ```sh
+npm run lint
 npm run check
 npm test
 npm run test:agent
 npm run build
 ```
 
+Run `npm run format` to apply Prettier formatting before committing. It uses
+four-space indentation and a 100-column target for supported source, config and
+documentation files, including Svelte components. Python, shell and game scripts
+are outside Prettier's supported languages. Generated agent downloads and the npm
+lockfile keep their generator's formatting.
+
+`npm run lint` checks formatting without changing files, then runs the recommended
+JavaScript, TypeScript and Svelte ESLint rules. Generated build output and local
+runtime data are excluded. Type checking remains part of `npm run check`.
+The ESLint config documents exceptions for existing Svelte navigation, list and
+reactivity patterns. Individual suppressions explain intentional validation and
+test fixtures. Node.js 22.13 is the minimum supported 22.x version for the lint
+toolchain.
+
 The `package.json` overrides keep SvelteKit 2 on patched `devalue` 5.x (5.9.4 or
 newer) and `cookie` 0.7.x releases until its dependency ranges include those fixes.
 These dependencies ship in the server bundle even though SvelteKit is a
@@ -103,17 +118,17 @@ T5/T6 server validation use the [host acceptance checklist](../guides/native-hos
 
 Paths below are relative to the repository root.
 
-| Path | Responsibility |
-| --- | --- |
-| `src/routes` | Pages and API endpoints |
-| `src/lib/ui` | Shared components, stores and [UI patterns](ui-patterns.md) |
-| `src/lib/server/hosts` | Enrollment, readiness and command transport |
-| `src/lib/server/backends` | Instance identity and remote file access |
-| `src/lib/server/provisioning/native.ts` | Lifecycle and campaign queues connected to agents |
-| `src/lib/server/game-files` | Immutable uploads and streaming distribution |
-| `src/lib/server/db` | SQLite schema, migrations and shared artifact storage |
-| `src/lib/server/reports` | Metrics, leaderboard and capacity workers |
-| `agent` | Python service, installer, packaging and tests |
+| Path                                    | Responsibility                                              |
+| --------------------------------------- | ----------------------------------------------------------- |
+| `src/routes`                            | Pages and API endpoints                                     |
+| `src/lib/ui`                            | Shared components, stores and [UI patterns](ui-patterns.md) |
+| `src/lib/server/hosts`                  | Enrollment, readiness and command transport                 |
+| `src/lib/server/backends`               | Instance identity and remote file access                    |
+| `src/lib/server/provisioning/native.ts` | Lifecycle and campaign queues connected to agents           |
+| `src/lib/server/game-files`             | Immutable uploads and streaming distribution                |
+| `src/lib/server/db`                     | SQLite schema, migrations and shared artifact storage       |
+| `src/lib/server/reports`                | Metrics, leaderboard and capacity workers                   |
+| `agent`                                 | Python service, installer, packaging and tests              |
 
 ## Performance diagnostics
 

docs/development/ui-patterns.md

@@ -74,16 +74,16 @@ logs. Static values use text or state colors; the accent marks links and control
 
 ### Product language
 
-| Concept | Visible label |
-| --- | --- |
-| A managed game instance | Server; use the friendly map and lobby name |
-| Creating a server | Create server |
-| Removing a server | Remove server |
-| Favourite server | Pin |
-| Game does not answer | Not responding |
-| Games | Black Ops I / Black Ops II; BO1 / BO2 in compact labels |
-| Releasing file changes | Campaigns |
-| Player completion evidence | Present in final report / Not present in final report |
+| Concept                    | Visible label                                           |
+| -------------------------- | ------------------------------------------------------- |
+| A managed game instance    | Server; use the friendly map and lobby name             |
+| Creating a server          | Create server                                           |
+| Removing a server          | Remove server                                           |
+| Favourite server           | Pin                                                     |
+| Game does not answer       | Not responding                                          |
+| Games                      | Black Ops I / Black Ops II; BO1 / BO2 in compact labels |
+| Releasing file changes     | Campaigns                                               |
+| Player completion evidence | Present in final report / Not present in final report   |
 
 Keep internal values such as `t5`, `t6`, `destroy`, instance IDs, and filenames in
 API fields and technical details. User-facing actions use the labels above.