hotfix: plugin manager infinite loading
- frontend: RPC timeout (8s), try/catch/finally on reload, proper UI
states (loading/error/empty/list)
- frontend: reload() now sets loading=true, catches errors
- backend: tilde expansion (~/.config/verstak/plugins → /home/mirivlad/...)
- backend: ReloadPlugins returns diagnostics (count, summary string)
- backend: diagnostic logging in DiscoverPlugins (start/dirs/entries/results)
- backend: FormatDiscoverySummary helper
- testing: 11 headless tests for DiscoverPlugins (empty, missing, valid,
broken JSON, duplicate ID, multiple dirs, nonexistent mix)
mirivlad
3c613f0e44