docs: fix broken doxygen references and escape HTML tags

- modules.dox: remove references to non-existent sendspin modules
- access.dox: remove reference to deprecated pipewire-media-session
- dma-buf.dox: fix \ref EnumFormat to \ref SPA_PARAM_EnumFormat,
  fix \ref struct to struct \ref for spa_meta_sync_timeline
- pipewire.conf.5.md: add explicit {#synopsis} anchor for internal links
- pipewire-client.conf.5.md: fix audio_converter to audio_adapter ref
- pipewire-jack.conf.5.md: escape <id> HTML tags
- pipewire-props.7.md: fix monitor-prop__ to props__ for card profiles ref
- pipewire-pulse.1.md: fix pipewire-env ref to full anchor name
- pipewire.1.md: fix \ref CPU to \ref spa_cpu

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

doc/dox/config/pipewire-client.conf.5.md

@@ -104,7 +104,7 @@ Some of the properties refer to different aspects of the stream:
 A list of object properties that can be applied to streams can be found in
 \ref props__common_node_properties "pipewire-props(7) Common Node Properties"
 and
-\ref props__audio_converter_properties "pipewire-props(7) Audio Adapter Properties"
+\ref props__audio_adapter_properties "pipewire-props(7) Audio Adapter Properties"
 
 # STREAM RULES  @IDX@ client.conf stream.rules
 

doc/dox/config/pipewire-jack.conf.5.md

@@ -326,9 +326,9 @@ You can use this to link filters to devices. When there is no client connected t
 @PAR@ jack-env  PIPEWIRE_NODE
 \parblock
 ```
-PIPEWIRE_NODE=<id> <application>
+PIPEWIRE_NODE=\<id\> \<application\>
 ```
-Will sort the ports so that only the ports of the node with <id> are listed. You can use this to force an application to only deal with the ports of a certain node, for example when auto connecting.
+Will sort the ports so that only the ports of the node with \<id\> are listed. You can use this to force an application to only deal with the ports of a certain node, for example when auto connecting.
 \endparblock
 
 # AUTHORS

doc/dox/config/pipewire-props.7.md

@@ -906,7 +906,7 @@ See \ref spa_param_port_config for the meaning.
 ## Monitor properties
 
 @PAR@ monitor-prop  alsa.use-acp = true      # boolean
-Use \ref monitor-prop__alsa_card_profiles "ALSA Card Profiles" (ACP) for device configuration.
+Use \ref props__alsa_card_profiles "ALSA Card Profiles" (ACP) for device configuration.
 This autodetects available ALSA devices and configures port and hardware mixers.
 
 @PAR@ monitor-prop  alsa.use-ucm             # boolean

doc/dox/config/pipewire.conf.5.md

@@ -4,7 +4,7 @@ The PipeWire server configuration file
 
 \tableofcontents
 
-# SYNOPSIS
+# SYNOPSIS {#synopsis}
 
 *$PIPEWIRE_CONFIG_DIR/pipewire/pipewire.conf*