feat(FN-3079): add plugin dashboard views and dependency graph plugin

- Add plugin dashboard view registration and hosting across core, dashboard routes, and plugin SDK exports
- Integrate plugin-provided views into app navigation, mobile/header UI, and view state hooks with coverage
- Add fusion-plugin-dependency-graph example plugin with persisted storage, dashboard view UI, and manifest wiring
- Update plugin authoring and architecture docs for dashboard view extension points
- Add a changeset for @runfusion/fusion covering plugin dashboard view support

Fusion-Task-Id: FN-3079

plugins/fusion-plugin-dependency-graph/README.md

@@ -0,0 +1,11 @@
+# fusion-plugin-dependency-graph
+
+Plugin-provided top-level **Graph** dashboard view for Fusion.
+
+- Registers `dashboardViews: [{ viewId: "graph", placement: "more" }]`
+- Renders active task dependency graph for `triage`, `todo`, `in-progress`, `in-review`
+- Excludes `done` and `archived`
+- Persists drag positions in browser localStorage at:
+  - `kb:${projectId}:dependency-graph-positions`
+
+The first version uses a lightweight custom SVG/HTML renderer (no React Flow dependency).