fix: MD5→SHA-256, shellcheck warnings, and broken doc links

config_service.py: replace MD5 with SHA-256 for config change detection;
same semantics (equality comparison), no stored hashes affected.

Shell scripts — shellcheck warnings:
- diagnose_web_interface.sh: remove useless cat (SC2002)
- dev_plugin_setup.sh: restructure A&&B||C into if/then (SC2015)
- fix_assets_permissions.sh: remove unused REAL_HOME block (SC2034)
- install_web_service.sh: remove unused USER_HOME assignment (SC2034)
- diagnose_web_ui.sh: remove unused SUDO assignments (SC2034)
- diagnose_plugin_permissions.sh: remove unused BLUE color var (SC2034)
- first_time_install.sh: remove unused CLEAR var, PACKAGE_NAME
  assignment, and replace loop variable with _ (SC2034)

docs/PLUGIN_ARCHITECTURE_SPEC.md: fix 10 broken TOC anchor links to
include section numbers matching the actual headings (MD051).

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

scripts/dev/dev_plugin_setup.sh

@@ -203,7 +203,9 @@ link_github_plugin() {
         log_info "Repository already exists at $target_dir"
         if [[ -d "$target_dir/.git" ]]; then
             log_info "Updating repository..."
-            (cd "$target_dir" && git pull --rebase || true)
+            if cd "$target_dir"; then
+                git pull --rebase || true
+            fi
         fi
     else
         # Clone the repository

scripts/diagnose_plugin_permissions.sh

@@ -13,7 +13,6 @@ echo ""
 RED='\033[0;31m'
 GREEN='\033[0;32m'
 YELLOW='\033[1;33m'
-BLUE='\033[0;34m'
 NC='\033[0m' # No Color
 
 # Get the actual user

scripts/diagnose_web_interface.sh

@@ -41,7 +41,7 @@ if [ -f "$PROJECT_DIR/config/config.json" ]; then
     echo -e "${GREEN}✓ Config file found${NC}"
     
     # Check web_display_autostart setting
-    AUTOSTART=$(cat "$PROJECT_DIR/config/config.json" | grep -o '"web_display_autostart"[[:space:]]*:[[:space:]]*[a-z]*' | grep -o '[a-z]*$')
+    AUTOSTART=$(grep -o '"web_display_autostart"[[:space:]]*:[[:space:]]*[a-z]*' "$PROJECT_DIR/config/config.json" | grep -o '[a-z]*$')
     
     if [ "$AUTOSTART" == "true" ]; then
         echo -e "${GREEN}✓ web_display_autostart: true${NC}"

scripts/diagnose_web_ui.sh

@@ -16,11 +16,8 @@ YELLOW='\033[1;33m'
 NC='\033[0m' # No Color
 
 # Check if running as root or with sudo
-if [ "$EUID" -ne 0 ]; then 
+if [ "$EUID" -ne 0 ]; then
     echo -e "${YELLOW}Warning: Some checks require sudo. Running what we can...${NC}"
-    SUDO=""
-else
-    SUDO=""
 fi
 
 PROJECT_DIR="${HOME}/LEDMatrix"

scripts/fix_perms/fix_assets_permissions.sh

@@ -7,12 +7,6 @@ echo "Fixing LEDMatrix assets directory permissions..."
 
 # Get the real user (not root when running with sudo)
 REAL_USER=${SUDO_USER:-$USER}
-# Resolve the home directory of the real user robustly
-if command -v getent >/dev/null 2>&1; then
-    REAL_HOME=$(getent passwd "$REAL_USER" | cut -d: -f6)
-else
-    REAL_HOME=$(eval echo ~"$REAL_USER")
-fi
 REAL_GROUP=$(id -gn "$REAL_USER")
 
 # Get the project directory

scripts/install/install_web_service.sh

@@ -14,9 +14,6 @@ else
     ACTUAL_USER=$(whoami)
 fi
 
-# Get the home directory of the actual user
-USER_HOME=$(eval echo ~$ACTUAL_USER)
-
 # Determine the Project Root Directory (parent of scripts/install/)
 PROJECT_ROOT_DIR=$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)