docs(advanced): remove Statefulness, Locks page

The Specifics → Statefulness page now covers this material. Drops the
advanced/stateful.md file and its sidebar entry, and repoints the two
inbound links (locks.md, statefulness.md) at the Specifics page.

Author: claude

docs/.vitepress/config.mjs

@@ -215,10 +215,6 @@ export default defineConfig({
           { text: "Downporting", link: "/advanced/downporting" },
           { text: "Renaming", link: "/advanced/renaming" },
           { text: "Builder", link: "/advanced/builds" },
-          {
-            text: "Statefulness, Locks",
-            link: "/advanced/stateful",
-          },
           { text: "Local", link: "/advanced/local" },
           { text: "RFC Connector", link: "/advanced/rfc" },
           { text: "Fiori Elements Integration", link: "/advanced/fiori" },

docs/advanced/stateful.md

@@ -157,4 +157,4 @@ Does the app edit data at all?
         └── Combined (Lock at Save + Optimistic Check)
 ```
 
-For the underlying concepts and trade-offs of statefulness, see [Statefulness, Locks](../../advanced/stateful.md).
+For the underlying concepts and trade-offs of statefulness, see [Statefulness](./statefulness.md).

docs/development/specific/locks.md

@@ -55,5 +55,4 @@ A few rules of thumb:
 
 #### Related
 - [Locks](./locks.md) — strategies for locking business objects, including stateless and stateful patterns
-- [Statefulness, Locks (Advanced)](../../advanced/stateful.md) — deeper background on the underlying concept
 - [Performance](../../configuration/performance.md) — sizing considerations for productive deployments