fix(resources): unify container/resource classification with multi-fallback resolution (#425)

* fix(sidebar): add service name and config_files fallbacks for container-to-stack matching

Containers that predate Sencho's reorganization of compose files into
subdirectories carry stale Docker labels where the project name is set
to the COMPOSE_DIR basename (e.g. "compose") rather than the stack
directory name. The existing project name map and working_dir fallbacks
from PR #416 did not cover this case.

Added two new fallback strategies to getBulkStackStatuses:
- Match by com.docker.compose.service label against known stack names
- Extract stack name from com.docker.compose.project.config_files path

Also reused the existing isPathWithinBase utility for path containment
checks and hoisted path.resolve(COMPOSE_DIR) out of the per-container
loop.

* fix(resources): unify container/resource classification with multi-fallback resolution

Extract shared helpers (resolveContainerStack, resolveProjectLabel,
buildAbsDirMap) and apply them consistently across getClassifiedResources,
pruneManagedOnly, getDiskUsageClassified, and getBulkStackStatuses.

Fixes incorrect "External" tagging in Resources Hub for images, volumes,
and networks belonging to stacks that predate Sencho's compose file
reorganization. Also fixes the "active" plural on the dashboard
Containers card.

frontend/src/components/dashboard/ResourceGauges.tsx

@@ -113,7 +113,7 @@ export function ResourceGauges({ stats, systemStats }: ResourceGaugesProps) {
             <CursorProvider>
               <CursorContainer className="inline-flex items-baseline">
                 <span className="text-2xl font-medium font-mono tabular-nums tracking-tight text-stat-value">{stats.active}</span>
-                <span className="text-sm text-stat-subtitle ml-1.5">active</span>
+                <span className="text-sm text-stat-subtitle ml-1.5">{stats.active === 1 ? 'active' : 'actives'}</span>
               </CursorContainer>
               <Cursor>
                 <div className="h-2 w-2 rounded-full bg-brand" />