docs(usb): Move USB docs to esp-usb and add redirects

Remove USB Host/Device content from ESP-IDF pages and keep only links to
ESP-USB documentation.

Add redirects for legacy USB pages to ESP-USB with target-aware URL
substitution in docs config.

Drop obsolete USB host notes references from docs_not_updated lists.

docs/conf_common.py

@@ -157,14 +157,6 @@ SPIRAM_DOCS = ['api-guides/external-ram.rst']
 USB_DOCS = [
     'api-reference/peripherals/usb_device.rst',
     'api-reference/peripherals/usb_host.rst',
-    'api-reference/peripherals/usb_host/usb_host_notes_arch.rst',
-    'api-reference/peripherals/usb_host/usb_host_notes_design.rst',
-    'api-reference/peripherals/usb_host/usb_host_notes_dwc_otg.rst',
-    'api-reference/peripherals/usb_host/usb_host_notes_index.rst',
-    'api-reference/peripherals/usb_host/usb_host_notes_usbh.rst',
-    'api-reference/peripherals/usb_host/usb_host_notes_enum.rst',
-    'api-reference/peripherals/usb_host/usb_host_notes_ext_hub.rst',
-    'api-reference/peripherals/usb_host/usb_host_notes_ext_port.rst',
 ]
 
 I80_LCD_DOCS = ['api-reference/peripherals/lcd/i80_lcd.rst']
@@ -509,6 +501,20 @@ QEMU_TARGETS = ['esp32', 'esp32c3', 'esp32s3']
 ESP_TEE_TARGETS = ['esp32c6', 'esp32h2', 'esp32c5', 'esp32c61']
 
 
+def _resolve_redirect_page_macros(redirect_pages, target):
+    replace_map = {
+        '{IDF_TARGET_PATH_NAME}': target,
+    }
+
+    resolved_redirect_pages = []
+    for old_url, new_url in redirect_pages:
+        for macro, value in replace_map.items():
+            new_url = new_url.replace(macro, value)
+        resolved_redirect_pages.append((old_url, new_url))
+
+    return resolved_redirect_pages
+
+
 # Callback function for user setup that needs be done after `config-init`-event
 # config.idf_target is not available at the initial config stage
 def conf_setup(app, config):
@@ -531,6 +537,8 @@ def conf_setup(app, config):
         # Not for all target
         pass
 
+    config.html_redirect_pages = _resolve_redirect_page_macros(config.html_redirect_pages, config.idf_target)
+
     config.html_baseurl = f'https://docs.espressif.com/projects/esp-idf/{config.language}/stable/{config.idf_target}'