feat(settings): report which saved keys need a restart

Every settings update answered with a bare success, so the console could not
tell a change that took effect at once from one written to the file that the
running program would keep ignoring until it was restarted — the listener
address, the storage paths, the Komari dashboard URL.

Classify the patch instead. config.RestartRequiredKeys expands a patch into the
dot-separated paths of its leaves and intersects them with the settings main
reads before it starts serving, and the settings endpoint returns that list as
data.restartRequired. It is a pure function of the patch, so UpdateSettings
keeps its signature and nothing else has to change; the write succeeds either
way, and the field only says which edits are not live.

Matching is by overlap rather than equality, so a patch that names a section —
replacing it, or deleting it with a null — reports the startup-only keys inside
it, while a sibling subtree like webhook.endpoints is not mistaken for
webhook.enabled.

The result is never nil, so an update with nothing to report serializes as []
rather than null and a client can iterate it without a guard.

The console reads the field in ConfigSection and warns instead of confirming,
naming the keys that are pending; Settings.vue's hints for the Komari URL, the
listen address and the storage paths now say which of their fields is affected
rather than labelling the whole card.

README.md

@@ -334,7 +334,7 @@ Browser WebSocket handshakes cannot carry custom headers, so `/api/system/getLog
 | `/api/server/getStatus` | GET | admin | Live server status (mirrors the Bot's `/status`). Query `?uuid=<uuid>` (or `all`). Returns `data: {<uuid>: {uuid, name, online, report}}`; `report` is `null` when the node has not reported yet. `404` for an unknown single uuid. |
 | `/api/server/exec` | POST | bot / admin | Execute a command. Body `{uuid: [<uuid>...], command}`. Dispatches a Komari task and polls until completion (or timeout). Returns `data: {taskID, results}`. |
 | `/api/settings/get` | GET | admin | `?type=global\|bot_user_config\|bot_node_config` | Returns `data: {config}`, where `config` is the selected config file's content (same layout as the JSON file). |
-| `/api/settings/set` | POST | admin | `?type=<same types>` + JSON body of partial updates, e.g. `{"system":{"debugMode":true}}` | Deep-merges the body into the selected config file, persists it, and reloads it in memory. Only the given keys change; arrays replace. See [What applies without a restart](#what-applies-without-a-restart). |
+| `/api/settings/set` | POST | admin | `?type=<same types>` + JSON body of partial updates, e.g. `{"system":{"debugMode":true}}` | Deep-merges the body into the selected config file, persists it, and reloads it in memory. Only the given keys change; arrays replace. Returns `data: {type, restartRequired}`, where `restartRequired` lists the keys the update changed that are only read at startup (see [What applies without a restart](#what-applies-without-a-restart)) — the write succeeds regardless, this only says which edits are not live yet. Always an array, empty when everything took effect. |
 | `/api/webhook/add` | POST | admin | Add an incoming webhook endpoint. Body `{name, enabled?, token?, notifyPipes?}` — only the fields given are stored, the rest start at their defaults. `409` when the name is already configured. |
 | `/api/webhook/modify` | POST | admin | Change an existing endpoint. Body `{name, ...}` — the fields given are the fields that change (same partial-update rule as `/api/settings/set`, but scoped to one endpoint). `404` for an unknown name, `400` when no other field is given. |
 | `/api/webhook/delete` | POST | admin | Remove an endpoint. Body `{name}`. `404` for an unknown name. |