docs(router): a leading slash is a full path under a base

src/routes/(4)routing/(1)solid-router/(1)setup.mdx

@@ -120,7 +120,7 @@ The other options exist for a specific situation each:
 
 | Option              | Reach for it when                                                                                                                 |
 | ------------------- | --------------------------------------------------------------------------------------------------------------------------------- |
-| `base`              | The app is served under a prefix such as `/app`; matching and `paths` both include it.                                            |
+| `base`              | The app is served under a prefix such as `/app`; matching and `paths` include it, and a string starting with `/` is a full path.  |
 | `history`           | The app is not a normal page: an Electron shell or `file://` needs `hashHistory()`, tests need `memoryHistory()`.                 |
 | `preload`           | The root layout needs data of its own; it runs once per mount or server request and reaches the function child as `props.data`.   |
 | `preloadLinks`      | Links should warm route code and data before the click; pass `intentPreload()` or another strategy (off by default).              |
@@ -131,6 +131,16 @@ The other options exist for a specific situation each:
 | `singleFlight`      | The router's server-function data consumer should be off; it is `true` by default.                                                |
 | `actionBase`        | Server functions are served from a prefix other than the default `/_server`.                                                      |
 
+When Vite serves the app under a `base`, pass `import.meta.env.BASE_URL` as the router `base` and link with `paths`.
+A `paths` node includes the base, so links, `navigate`, and `redirect` stay under it:
+
+```tsx
+export const Router = createRouter({
+	routes,
+	base: import.meta.env.BASE_URL,
+});
+```
+
 The router uses browser history by default on the client and the current request URL on the server, so `history` is rarely set in a web app:
 
 ```tsx

src/routes/(4)routing/(1)solid-router/(4)navigation.mdx

@@ -95,7 +95,10 @@ function CheckoutButton() {
 Click the button and the URL becomes `/checkout` with the cart page's history entry replaced, so **Back** returns to the page before the cart rather than to the cart.
 
 The options are the same as the link attributes: `replace`, `scroll`, and `state`, plus `resolve` for how a relative string is interpreted.
-A string starting with `/` resolves under the router's `base`; other strings resolve against the current location like a relative URL.
+A string starting with `/` is a full path, and the router does not add its `base` to it: under `base: "/app"`, `navigate("/about")` goes to `/about`.
+Pass a `paths` node, such as `paths.about`, for a path under the base; a node already includes the base.
+A full path outside the base is another document, so `navigate` loads it, as a link or a redirect to it does.
+Other strings resolve against the current location like a relative URL.
 A number moves through history: `navigate(-1)` is back.
 
 :::tip[Let the server decide where to go]

src/routes/(6)migration/(3)from-solid-router.mdx

@@ -296,6 +296,12 @@ function LoginRedirect() {
 }
 ```
 
+Under a `base`, a string that starts with `/` is now a full path.
+With `base: "/app"`, Solid Router 0.x/1.x sent `navigate("/login")` and `<A href="/login">` to `/app/login`; Solid Router 2 sends them to `/login`.
+The same applies to `useResolvedPath`, `useLinkState`, and `redirect`.
+Use a `paths` node, such as `Router.paths.login`, which includes the base.
+A full path outside the base loads the document.
+
 Rename `useCurrentMatches` to `useRouteMatches`.
 Use `useLinkState` when a custom link component needs reactive `active`, `current`, or `pending` values.
 See [Navigation and typed paths](/routing/solid-router/navigation) for the remaining anchor and navigation options.

src/routes/reference/(3)solid-router/(1)router-factory.mdx

@@ -53,7 +53,7 @@ interface RouterConfig<
 ```
 
 - `routes` is the route tree used for matching and path inference.
-- `base` prefixes matched and generated paths.
+- `base` prefixes route matching and `paths` nodes. A string that starts with `/` is a full path everywhere (`href`, `navigate`, `useLinkState`, `useResolvedPath`, and `redirect`), and the router does not add `base` to it.
 - `preload` returns data for the root render prop.
 - `history` defaults to browser history on the client.
 - `singleFlight` defaults to `true`.

src/routes/reference/(3)solid-router/(3)navigation.mdx

@@ -196,6 +196,7 @@ function useResolvedPath(path: () => string): () => string | undefined;
 ```
 
 Resolves a path against the current route context.
+A path that starts with `/` is already a full path, so the router does not add its `base` to it.
 
 ## `useHref`