feat(editor): type-token coloring + analyzer diagnostics

The text tab now colours `type: text|json|bytes|file|number`
values in the same hues the graph canvas uses for the wire of
that type — a glance at the YAML confirms what a glance at the
graph shows. Promoted the wire-colour palette to a single
source of truth in `wire_colors.dart` so the graph, the
properties panel and the text tab can't drift.

Adds `FlowAnalyzer` (extends `AbstractAnalyzer`) so the gutter
shows error pins and broken lines get wavy red underlines for:

  - YAML parse errors (source-span pinned to the offending line)
  - `use:` referencing a capability the operator hasn't installed
    (bare provider/name match — `text.echo@^1` and `text.echo`
    compare equal)

Editor host passes a closure into `setAvailableCapabilities` so
the analyser always sees the current installed list without
re-creating the controller on every Studio rebuild. Bumps the
package version to 0.15.0.

Signed-off-by: flemming-it <sf@flemming.it>

lib/src/flow_editor_page.dart

@@ -100,6 +100,9 @@ class _FlowEditorPageState extends State<FlowEditorPage>
     super.initState();
     _l = FlowEditorStrings(widget.locale);
     _controller = FlowEditorController();
+    _controller.codeController.setAvailableCapabilities(
+      () => widget.availableCapabilities,
+    );
     _controller.addListener(_onCtrlChanged);
     _tabs = TabController(length: 3, vsync: this);
     _files = _listFiles();