docs(scripts): monorepo workspace layout; fix_perms and install READMEs

MULTI_ROOT_WORKSPACE_SETUP described one sibling repository per plugin;
setup_plugin_repos.py links ../ledmatrix-plugins/plugins/* into
plugin-repos/ and update_plugin_repos.py pulls only the monorepo, and the
workspace file opens LEDMatrix plus ../ledmatrix-plugins.

scripts/fix_perms/README.md listed cache directories
fix_cache_permissions.sh never touches and a 'ledmatrix' service user
that doesn't exist (also in scripts/install/README.md); adds
safe_pip_install.sh. install/README: install_service.sh installs the web
and update-verify units too.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/fix_perms/README.md

@@ -7,8 +7,10 @@ install as the wrong user, after a manual file copy that didn't preserve
 ownership, or after a permissions-related error from the display or
 web service.
 
-Most of these scripts require `sudo` since they touch directories
-owned by the `ledmatrix` service user or by `root`.
+Most of these scripts require `sudo` since they touch directories owned
+by `root` (the display service's user) or by the user you installed
+LEDMatrix as (the web service's user). There is no dedicated `ledmatrix`
+system user.
 
 ## Scripts
 
@@ -16,11 +18,12 @@ owned by the `ledmatrix` service user or by `root`.
   permissions on the `assets/` tree so plugins can download and cache
   team logos, fonts, and other static content.
 
-- **`fix_cache_permissions.sh`** — Fixes permissions on every cache
-  directory the project may use (`/var/cache/ledmatrix/`,
-  `~/.cache/ledmatrix/`, `/opt/ledmatrix/cache/`, project-local
-  `cache/`). Also creates placeholder logo subdirectories used by the
-  sports plugins.
+- **`fix_cache_permissions.sh`** — Creates (if missing) and fixes
+  permissions on `/var/cache/ledmatrix/` and `~/.ledmatrix_cache/` of the
+  user running `sudo`, and creates
+  `/var/cache/ledmatrix/placeholder_logos/` for the sports plugins. It does
+  not touch the cache manager's other fallbacks (`/opt/ledmatrix/cache`,
+  `$TMPDIR/ledmatrix_cache`).
 
 - **`fix_plugin_permissions.sh`** — Fixes ownership on the plugins
   directory so both the root display service and the web service user
@@ -31,6 +34,11 @@ owned by the `ledmatrix` service user or by `root`.
   systemd journal access, and the sudoers entries the web interface
   needs to control the display service.
 
+- **`safe_pip_install.sh`** — Installs a `requirements.txt` as root
+  after checking it is the project's own or one under `plugin-repos/` or
+  `plugins/`. Used by the web interface (via sudo) to install plugin
+  dependencies where `ledmatrix.service` can import them.
+
 - **`safe_plugin_rm.sh`** — Validates that a plugin removal path is
   inside an allowed base directory before deleting it. Used by the web
   interface (via sudo) when a user clicks **Uninstall** on a plugin —

scripts/install/README.md

@@ -7,14 +7,18 @@ This directory contains scripts for installing and configuring the LEDMatrix sys
 - **`one-shot-install.sh`** - Single-command installer; clones the
   repo, checks prerequisites, then runs `first_time_install.sh`.
   Invoked via `curl ... | bash` from the project root README.
-- **`install_service.sh`** - Installs the main LED Matrix display service (systemd)
-- **`install_web_service.sh`** - Installs the web interface service (systemd)
+- **`install_service.sh`** - Installs, enables and starts the display
+  service (`ledmatrix.service`), the web interface service
+  (`ledmatrix-web.service`) and the update-verify units (systemd)
+- **`install_web_service.sh`** - Installs only the web interface service
+  and the update-verify units (systemd)
 - **`install_wifi_monitor.sh`** - Installs the WiFi monitor daemon service
 - **`setup_cache.sh`** - Sets up persistent cache directory with proper permissions
 - **`configure_web_sudo.sh`** - Configures passwordless sudo access for web interface actions
-- **`configure_wifi_permissions.sh`** - Grants the `ledmatrix` user
-  the WiFi management permissions needed by the web interface and
-  the WiFi monitor service
+- **`configure_wifi_permissions.sh`** - Grants the web interface's user
+  (the user who runs the script, i.e. the one you installed LEDMatrix as;
+  there is no `ledmatrix` system user) the passwordless `nmcli` and related
+  WiFi permissions the web interface needs
 - **`migrate_config.sh`** - Migrates configuration files to new formats (if needed)
 - **`debug_install.sh`** - Diagnostic helper used when an install
   fails; collects environment info and recent logs