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>

pubspec.yaml

@@ -1,6 +1,6 @@
 name: fai_studio_flow_editor
 description: Swappable inline YAML editor for F∆I Studio flows.
-version: 0.14.0
+version: 0.15.0
 publish_to: 'none'
 repository: https://git.flemming.ai/fai/studio-flow-editor