FN-6019: make dependency graph fill full dashboard width

Ensure the bundled dependency graph stretches to the full available dashboard width.

- add flex sizing and min-width rules so the dependency graph fills its parent container
- cover empty-state and populated mobile-width layouts with CSS-backed flex sizing assertions
- add a patch changeset for the published CLI bundle

Files changed:
 .changeset/sharp-graphs-stretch.md                 |  5 +++
 plugins/fusion-plugin-dependency-graph/src/DependencyGraph.css                        |  3 ++
 plugins/fusion-plugin-dependency-graph/src/__tests__/DependencyGraph.test.tsx         | 44 ++++++++++++++++++++++
 3 files changed, 52 insertions(+)

Fusion-Task-Id: FN-6019

Fusion-Task-Lineage: a34b2bdd-d489-4e84-9604-e6265bce733a

plugins/fusion-plugin-dependency-graph/src/DependencyGraph.css

@@ -1,5 +1,8 @@
 .dependency-graph {
   position: relative;
+  flex: 1 1 auto;
+  min-width: 0;
+  box-sizing: border-box;
   height: 100%;
   padding: var(--space-md);
 }