docs: rebuild the v2 documentation around a task-based page tree (#2397)

docs/migration/index.md

@@ -50,5 +50,5 @@ the codemod first; the guide is the codemod's companion for what's left.
 ## See also
 
 - [`@modelcontextprotocol/codemod` README](https://github.com/modelcontextprotocol/typescript-sdk/blob/main/packages/codemod/README.md)
-- [FAQ](../faq.md)
+- [Troubleshooting](../troubleshooting.md)
 - [Examples](https://github.com/modelcontextprotocol/typescript-sdk/tree/main/examples)

docs/migration/support-2026-07-28.md

@@ -38,14 +38,14 @@ below.
 
 ## Serving the 2026-07-28 revision
 
-These entry points are documented in full in the server and client guides; this section
-contextualizes them as the migration path.
+These entry points are documented in full in [Protocol versions](../protocol-versions.md);
+this section contextualizes them as the migration path.
 
 ### Client side: `versionNegotiation`
 
 By default `Client.connect()` performs the same 2025 `initialize` handshake as v1.x,
 byte for byte. To negotiate the 2026-07-28 era, opt in via `ClientOptions.versionNegotiation` —
-see [client.md › Protocol version negotiation](../client.md#protocol-version-negotiation-2026-07-28-revision).
+see [Negotiate the era from the client](../protocol-versions.md#negotiate-the-era-from-the-client).
 
 ```typescript
 const client = new Client({ name: 'my-client', version: '1.0.0' }, { versionNegotiation: { mode: 'auto' } });
@@ -166,7 +166,7 @@ on the wire. Serving 2026-07-28 (or both eras) on stdio goes through the
 connection-pinned `serveStdio(() => buildServer())` entry from
 `@modelcontextprotocol/server/stdio`; the opening exchange selects the connection's era,
 and one factory instance is pinned per connection. See
-[server.md › Serving the 2026-07-28 draft revision on stdio](../server.md#serving-the-2026-07-28-draft-revision-on-stdio).
+[Serve over stdio](../serving/stdio.md).
 
 To migrate an existing stdio server, replace
 `await server.connect(new StdioServerTransport())` with

docs/migration/upgrade-to-v2.md

@@ -1145,7 +1145,7 @@ version negotiation. Under the probing modes (`versionNegotiation: { mode: 'auto
 with or without a pin) the connect-time 401 currently surfaces wrapped as
 `SdkError(SdkErrorCode.EraNegotiationFailed)` with the `UnauthorizedError` at
 `error.data.cause` — unwrap before the check, as shown in the
-[client guide's authentication section](../client.md#authentication).
+[client OAuth guide](../clients/oauth.md).
 
 #### `auth()` options are now `AuthOptions`
 
@@ -1777,7 +1777,7 @@ where an entry notes its own signature change:
 - `StreamableHTTPClientTransport`, `SSEClientTransport` constructors and options —
   including resumability: the per-request `resumptionToken` / `onresumptiontoken`
   request options carry over from v1 unchanged
-  ([Resumption tokens](../client.md#resumption-tokens) in the client guide).
+  ([Resume a dropped stream](../serving/sessions-state-scaling.md#resume-a-dropped-stream)).
 - `StdioClientTransport` and `StdioServerTransport` — **import path moved** to the
   `./stdio` subpath and gained an optional `maxBufferSize` ([Imports & transports](#imports--transports)).
 - The **`Transport` interface contract** — `start` / `send` / `close`, `onmessage` /
@@ -1809,7 +1809,7 @@ where an entry notes its own signature change:
 
 - The codemod's [`@mcp-codemod-error`](https://github.com/modelcontextprotocol/typescript-sdk/blob/main/packages/codemod/README.md) markers point
   at every site it could not safely rewrite.
-- The [FAQ](../faq.md) covers common v2 questions.
+- The [Troubleshooting](../troubleshooting.md) page covers common errors and their fixes.
 - Runnable [examples](https://github.com/modelcontextprotocol/typescript-sdk/tree/main/examples)
   for every subsystem.
 - Open an issue on [GitHub](https://github.com/modelcontextprotocol/typescript-sdk/issues).