Add universal volume management operations

- volumes-clean-all: Clean all project volumes with confirmation
- volumes-clean-postgres: Clean only PostgreSQL data volumes
- volumes-clean-servapp: Clean only ServApp data volumes
- volumes-list: List project volumes by prefix

All commands use universal runtime detection from core.just

volumes.just

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+# Universal volume management operations
+
+# Clean all volumes (DESTRUCTIVE!)
+[group: 'volumes']
+volumes-clean-all project_prefix compose-file="compose.yml":
+    #!/usr/bin/env bash
+    set -euo pipefail
+
+    project_prefix="{{project_prefix}}"
+    compose_file="{{compose-file}}"
+
+    if [ -z "$project_prefix" ]; then
+        echo "Error: Project prefix is required" >&2
+        echo "Usage: just volumes-clean-all myproject" >&2
+        exit 1
+    fi
+
+    compose_cmd=$(just _detect_compose)
+
+    echo -e "{{RED}}⚠️  WARNING: This will DELETE ALL DATA!{{NC}}"
+    echo -e "{{YELLOW}}This will remove all volumes: postgres_data, postgres_lib, servapp_data, servapp_logs{{NC}}"
+    read -p "Are you sure? Type 'yes' to continue: " confirm
+
+    if [ "$confirm" != "yes" ]; then
+        echo "Aborted"
+        exit 1
+    fi
+
+    echo -e "{{BLUE}}Stopping services...{{NC}}"
+    $compose_cmd -f "$compose_file" down
+
+    echo -e "{{BLUE}}Removing volumes...{{NC}}"
+    $compose_cmd -f "$compose_file" down -v
+
+    echo -e "{{GREEN}}✓ All volumes removed{{NC}}"
+
+# Clean only PostgreSQL data volume (DESTRUCTIVE!)
+[group: 'volumes']
+volumes-clean-postgres project_prefix:
+    #!/usr/bin/env bash
+    set -euo pipefail
+
+    project_prefix="{{project_prefix}}"
+
+    if [ -z "$project_prefix" ]; then
+        echo "Error: Project prefix is required" >&2
+        echo "Usage: just volumes-clean-postgres myproject" >&2
+        exit 1
+    fi
+
+    runtime=$(just _detect_runtime)
+
+    echo -e "{{RED}}⚠️  WARNING: This will DELETE PostgreSQL DATA!{{NC}}"
+    echo -e "{{YELLOW}}This will remove postgres_data and postgres_lib volumes{{NC}}"
+    read -p "Are you sure? Type 'yes' to continue: " confirm
+
+    if [ "$confirm" != "yes" ]; then
+        echo "Aborted"
+        exit 1
+    fi
+
+    echo -e "{{BLUE}}Stopping PostgreSQL service...{{NC}}"
+    just stop
+
+    echo -e "{{BLUE}}Removing PostgreSQL volumes...{{NC}}"
+    $runtime volume rm servass_${project_prefix}_postgres_data servass_${project_prefix}_postgres_lib 2>/dev/null || true
+
+    echo -e "{{GREEN}}✓ PostgreSQL volumes removed{{NC}}"
+    echo -e "{{YELLOW}}Run 'just start' to create fresh PostgreSQL instance{{NC}}"
+
+# Clean only ServApp data volume (DESTRUCTIVE!)
+[group: 'volumes']
+volumes-clean-servapp project_prefix app_container compose-file="compose.yml":
+    #!/usr/bin/env bash
+    set -euo pipefail
+
+    project_prefix="{{project_prefix}}"
+    app_container="{{app_container}}"
+    compose_file="{{compose-file}}"
+
+    if [ -z "$project_prefix" ]; then
+        echo "Error: Project prefix is required" >&2
+        echo "Usage: just volumes-clean-servapp myproject myapp" >&2
+        exit 1
+    fi
+
+    if [ -z "$app_container" ]; then
+        echo "Error: App container name is required" >&2
+        echo "Usage: just volumes-clean-servapp myproject myapp" >&2
+        exit 1
+    fi
+
+    runtime=$(just _detect_runtime)
+
+    echo -e "{{RED}}⚠️  WARNING: This will DELETE ServApp DATA!{{NC}}"
+    echo -e "{{YELLOW}}This will remove servapp_data and servapp_logs volumes{{NC}}"
+    read -p "Are you sure? Type 'yes' to continue: " confirm
+
+    if [ "$confirm" != "yes" ]; then
+        echo "Aborted"
+        exit 1
+    fi
+
+    echo -e "{{BLUE}}Stopping ServApp service...{{NC}}"
+    compose_cmd=$(just _detect_compose)
+    $compose_cmd -f "$compose_file" stop "$app_container"
+
+    echo -e "{{BLUE}}Removing ServApp volumes...{{NC}}"
+    $runtime volume rm servass_${project_prefix}_servapp_data servass_${project_prefix}_servapp_logs 2>/dev/null || true
+
+    echo -e "{{GREEN}}✓ ServApp volumes removed{{NC}}"
+    echo -e "{{YELLOW}}Run 'just start' to recreate ServApp with fresh data{{NC}}"
+
+# List project volumes
+[group: 'volumes']
+volumes-list project_prefix:
+    #!/usr/bin/env bash
+    set -euo pipefail
+
+    project_prefix="{{project_prefix}}"
+
+    if [ -z "$project_prefix" ]; then
+        echo "Error: Project prefix is required" >&2
+        echo "Usage: just volumes-list myproject" >&2
+        exit 1
+    fi
+
+    runtime=$(just _detect_runtime)
+
+    echo -e "{{BLUE}}Project volumes:{{NC}}"
+    $runtime volume ls | grep "servass_${project_prefix}" || echo "No servass_${project_prefix} volumes found"