[DOC] Add redirects for moved ExecuTorch pages (pytorch#19338)

Fixes pytorch#14797

### Summary

- Add redirects for moved top-level backend, LLM, and tutorial pages.
- Point existing Core ML, MPS, and Arm Ethos-U redirects at their
current canonical pages.
- Update stale internal doc links, including the Tools Model
Visualization entry.
- Keep Samsung Exynos in Android navigation through the Android wrapper
while preserving the Backends section order so Cadence points next to
Samsung.

### Test plan

- `git diff --check`
- `python -m py_compile docs/source/conf.py`
- Redirect-target script: checked 23 redirects, no missing targets
- Parsed redirect table: confirmed `llm/llama-demo-android` resolves to
`docs/source/using-executorch-android.md`
- `PYTHONPATH=/tmp/executorch-doc-stub:.. ../.venv/bin/sphinx-build -D
plot_gallery=0 -b html docs/source
/tmp/executorch-docs-14797-final-escalated` succeeded with existing
repository warnings before the follow-up redirect entry
- Verified rendered `backends-cadence.html` next page is Samsung Exynos
- Verified generated redirects for `backends-arm-ethos-u.html`,
`backends-coreml.html`, `backends-mps.html`, and `visualization.html`


cc @digantdesai @freddan80 @per @zingo @oscarandersson8218 @mansnils
@Sebastian-Larsson @robell

Author: ymrohit

docs/source/android-backends.md

@@ -16,7 +16,7 @@ Available hardware acceleration backends for Android deployment.
 - {doc}`android-qualcomm` — Qualcomm AI Engine (NPU)
 - {doc}`android-mediatek` — MediaTek NPU acceleration
 - {doc}`android-arm-vgf` — ARM VGF Backend
-- {doc}`backends/samsung/samsung-overview` — Samsung Exynos NPU
+- {doc}`android-samsung-exynos` — Samsung Exynos NPU
 
 ```{toctree}
 :hidden:
@@ -25,4 +25,5 @@ android-vulkan
 android-qualcomm
 android-mediatek
 android-arm-vgf
-backends/samsung/samsung-overview
+android-samsung-exynos
+```

docs/source/backends/arm-ethos-u/arm-ethos-u-overview.md

@@ -4,7 +4,7 @@ The Arm® Ethos™-U backend targets Edge/IoT-type AI use-cases by enabli
 [Arm® Ethos™-U55 NPU](https://www.arm.com/products/silicon-ip-cpu/ethos/ethos-u55), [Arm® Ethos™-U65 NPU](https://www.arm.com/products/silicon-ip-cpu/ethos/ethos-u65), and
 [Arm® Ethos™-U85 NPU](https://www.arm.com/products/silicon-ip-cpu/ethos/ethos-u85), leveraging [TOSA](https://www.mlplatform.org/tosa/) and the
 [ethos-u-vela](https://pypi.org/project/ethos-u-vela/) graph compiler. This document is a technical reference for using the Ethos-U backend, for a top level view with code examples
-please refer to the [Arm Ethos-U Backend Tutorial](https://docs.pytorch.org/executorch/stable/tutorial-arm-ethos-u.html).
+please refer to the [Arm Ethos-U Backend Tutorial](tutorials/ethos-u-getting-started.md).
 
 ## Features
 
@@ -111,7 +111,7 @@ For more information on quantization, see [Quantization](arm-ethos-u-quantizatio
 
 ## Runtime Integration
 
-An example runtime application is available in [examples/arm/executor_runner](https://github.com/pytorch/executorch/blob/main/examples/arm/executor_runner/), and the steps requried for building and deploying it on a FVP it is explained in the previously mentioned [Arm Ethos-U Backend Tutorial](https://docs.pytorch.org/executorch/stable/tutorial-arm-ethos-u.html).
+An example runtime application is available in [examples/arm/executor_runner](https://github.com/pytorch/executorch/blob/main/examples/arm/executor_runner/), and the steps requried for building and deploying it on a FVP it is explained in the previously mentioned [Arm Ethos-U Backend Tutorial](tutorials/ethos-u-getting-started.md).
 The example application is recommended to use for testing basic functionality of your lowered models, as well as a starting point for developing runtime integrations for your own targets.
 For an in-depth explanation of the architecture of the executor_runner and the steps required for doing such an integration, please refer to [Ethos-U porting guide](https://github.com/pytorch/executorch/blob/main/examples/arm/ethos-u-porting-guide.md).
 

docs/source/conf.py

@@ -283,13 +283,23 @@
     "tutorials/export-to-executorch-tutorial": "../using-executorch-export.html",
     "build-run-vulkan": "backends/vulkan/vulkan-overview.html",
     "backends-vulkan": "backends/vulkan/vulkan-overview.html",
-    "executorch-arm-delegate-tutorial": "backends-arm-ethos-u.html",
-    "build-run-coreml": "backends-coreml.html",
+    "executorch-arm-delegate-tutorial": "backends/arm-ethos-u/tutorials/ethos-u-getting-started.html",
+    "build-run-coreml": "backends/coreml/coreml-overview.html",
     "build-run-mediatek-backend": "backends-mediatek.html",
-    "build-run-mps": "backends-mps.html",
+    "build-run-mps": "backends/mps/mps-overview.html",
     "build-run-qualcomm-ai-engine-direct-backend": "backends-qualcomm.html",
     "build-run-xtensa": "backends-cadence.html",
     "apple-runtime": "using-executorch-ios.html",
+    "backends-arm-ethos-u": "backends/arm-ethos-u/arm-ethos-u-overview.html",
+    "backends-arm-vgf": "backends/arm-vgf/arm-vgf-overview.html",
+    "backends-coreml": "backends/coreml/coreml-overview.html",
+    "backends-mps": "backends/mps/mps-overview.html",
+    "backends-xnnpack": "backends/xnnpack/xnnpack-overview.html",
+    "backend-delegates-xnnpack-reference": "backends/xnnpack/xnnpack-arch-internals.html",
+    "llm/llama-demo-android": "../using-executorch-android.html",
+    "tutorial-arm-ethos-u": "backends/arm-ethos-u/tutorials/ethos-u-getting-started.html",
+    "tutorial-arm-vgf": "backends/arm-vgf/tutorials/vgf-getting-started.html",
+    "visualization": "visualize.html",
 }
 
 # Custom directives defintions to create cards on main landing page

docs/source/platforms-desktop.md

@@ -11,11 +11,11 @@ ExecuTorch supports desktop and laptop deployment across Linux, macOS, and Windo
 ### Linux
 - [XNNPACK (CPU)](backends/xnnpack/xnnpack-overview.md)
 - [OpenVINO (Intel)](build-run-openvino)
-- [ARM Ethos-U (ARM64)](backends-arm-ethos-u)
+- [ARM Ethos-U (ARM64)](backends/arm-ethos-u/arm-ethos-u-overview.md)
 
 ### macOS
-- [CoreML (recommended)](backends-coreml)
-- [MPS (Apple Silicon)](backends-mps)
+- [Core ML (recommended)](backends/coreml/coreml-overview.md)
+- [MPS (Apple Silicon)](backends/mps/mps-overview.md)
 - [XNNPACK (CPU)](backends/xnnpack/xnnpack-overview.md)
 
 ### Windows

docs/source/platforms-embedded.md

@@ -10,10 +10,10 @@ ExecuTorch supports embedded devices from microcontrollers to edge devices.
 
 ### Microcontrollers
 - [Cadence Xtensa Backend](backends-cadence)
-- [ARM Ethos-U NPU Backend](backends-arm-ethos-u)
+- [ARM Ethos-U NPU Backend](backends/arm-ethos-u/arm-ethos-u-overview.md)
 - [Custom Backend Development](backend-delegates-integration)
 
 ### Edge Devices
-- [ARM Ethos-U NPU Backend](backends-arm-ethos-u)
-- [NXP eIQ Neutron Backend](backend-nxp)
+- [ARM Ethos-U NPU Backend](backends/arm-ethos-u/arm-ethos-u-overview.md)
+- [NXP eIQ Neutron Backend](backends/nxp/nxp-overview.md)
 - [Custom Hardware Integration](backend-delegates-integration)

docs/source/tools-section.md

@@ -13,7 +13,7 @@ In this section, explore ExecuTorch's comprehensive developer tools for profilin
 - {doc}`model-inspector` — Model Inspector
 - {doc}`memory-planning-inspection` — Memory Planning Inspection
 - {doc}`devtools-tutorial` — Development Utilities
-- {doc}`visualization` — Model Visualization
+- {doc}`visualize` — Model Visualization
 
 ```{toctree}
 :hidden:
@@ -29,4 +29,4 @@ model-debugging
 model-inspector
 memory-planning-inspection
 devtools-tutorial
-visualization
+visualize

docs/source/using-executorch-export.md

@@ -38,7 +38,7 @@ Commonly used hardware backends are listed below. For mobile, consider using XNN
 - [Vulkan (Android GPU)](backends/vulkan/vulkan-overview.md)
 - [Qualcomm NPU](backends-qualcomm.md)
 - [MediaTek NPU](backends-mediatek.md)
-- [Arm Ethos-U NPU](backends-arm-ethos-u.md)
+- [Arm Ethos-U NPU](backends/arm-ethos-u/arm-ethos-u-overview.md)
 - [Cadence DSP](backends-cadence.md)
 
 ## Model Preparation