wire the output dock into the layout — toggle, tabs, persistence (T-54)

The D-87 bottom dock, end to end. New Slots.dock in the classic preset
(hidden by default); RootLayout renders it full-width above the status bar
when open, capped at half the window so Claude stays largest (the D-47
amendment). LogRing now lives on KernelServices (boot tees the kernel logger
into it; main.dart also tees the IPC/MCP logger), so the dock shows logs from
every subsystem.

OutputExtension contributes the Output tab, the merged health/toggle
status-bar widget (green check when clean, warn/error counts otherwise) that
replaces the old ipc-status item, and the dock.toggle command (Ctrl+J).
Problems moves out of the sidebar into the dock. open/height persist per
workspace via the default-layout extension.

Drag-resize of the dock height is deferred (DragResizeHandle needs a dock
sign case); height is the persisted default for now. Boot verified via
testmode; full suite green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -18,6 +18,11 @@ heading, and (b) bumping `pubspec.yaml` `version:` in the same commit.
 
 ### Added
 
+- A bottom **output dock**: toggle it from a status-bar widget (or `⌘J`/`Ctrl+J`)
+  to see logs (Output) and diagnostics (Problems) as tabs — filterable by
+  source/level/text, auto-scrolling. The status widget doubles as a health
+  badge (green `✓` clean, `⚠`/`✕` counts otherwise) and replaces the old
+  app-status item; Problems moved here from the sidebar. (T-54, D-87)
 - External MCP clients (Cursor, Windsurf, Copilot, …) can now drive clide: the
   MCP server exposes the full `mcp__clide__*` tool surface, generated from the
   command registry that already feeds the CLI + palette (D-86), with a