feat: full multi-page UI with Status, History, Settings, and Deploy modal

Pages:
- Status: summary cards (pods/nodes), resource table with search/filter, event stream
- History: expandable apply log with YAML view, re-apply, search by prompt/provider/status
- Settings: 3-tab config (Providers/Cluster/Generation) with test buttons, toggles, sliders

Components:
- DeployModal: Write/Upload/URL input modes with deploy checklist
- LeftSidebar: accepts activeNav prop for page routing

Features:
- Ctrl+Enter prompt submission (already existed)
- Schema context chips showing detected resource types
- Provider selector dropdown in orchestrator header
- Validation status banner (pass/fail)
- Token/latency metadata footer on YAML editor
- Live deployments with inline undo + countdown timer
- Namespace selector ready for cluster integration
- Form inputs, toggles, sliders, test connection buttons
- Modal overlay with tabs, file upload, URL fetch

Author: Aamod