This PR enables hotkeys (L, p, n, s, d) to work on group headers (Control Plane, Workers) in the TUI, showing aggregated views for all nodes in that group. Users can toggle between Interleaved (all nodes merged by timestamp) and ByNode (tabbed per-node) display modes.

Group Hotkeys

When highlighting a Control Plane or Workers group header, the following hotkeys now work:

View Modes

• Interleaved (default): All data merged and sorted, with hostname: prefix to identify source
• ByNode: Tabbed interface showing one node's data at a time

New Keybindings (Group Views)

Changes to "core" functionality:

• action.rs - Added 5 new action variants (ShowGroupLogs, ShowGroupProcesses, ShowGroupNetwork, ShowGroupStorage, ShowGroupDiagnostics)
• cluster.rs - Added current_group_nodes() and common_services_for_group() helpers; updated hotkey handlers to detect group selection
• app.rs - Added handlers for all group actions with proper client setup for refresh

Components that were added:

• multi_logs.rs - Added GroupViewMode, multi-node streaming, view toggle, tab navigation
• processes.rs - Added group view support with new_group(), refresh_group(), view toggle
• network.rs - Added group view support with new_group(), refresh_group(), view toggle
• storage.rs - Added group view support with new_group(), refresh_group(), view toggle
• diagnostics/mod.rs - Added group view support with new_group(), refresh_group(), view toggle

Architecture

User presses 'L' on "Control Plane" header
    │
    ▼
cluster.rs: current_group_nodes() returns (group_name, role, nodes)
    │
    ▼
cluster.rs: Emits Action::ShowGroupLogs(group_name, role, nodes, services)
    │
    ▼
app.rs: Creates MultiLogsComponent::new_group()
    │
    ├─► Fetches initial logs from all nodes
    ├─► Sets client for refresh capability
    └─► Starts multi-node streaming
    │
    ▼
multi_logs.rs: Renders with GroupViewMode (Interleaved or ByNode)

View Mode Toggle Flow

Interleaved Mode                    ByNode Mode
┌─────────────────────┐            ┌─────────────────────┐
│ All nodes merged    │            │ [node1] [node2] ... │
│ sorted by timestamp │ ◄── v ──►  │ ─────────────────── │
│ hostname:service    │            │ Selected node only  │
└─────────────────────┘            └─────────────────────┘
                                        ▲         ▲
                                        │         │
                                       [←]       [→]
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Also added some Unit Tests:

No breaking changes. All existing functionality is preserved. Single-node hotkeys work exactly as before. Let me know if you hate anything/everything. I know that this many lines of code increases the maintenance burden, but hopefully this adds enough features to be worth it.