Graph instances never disposed on tab close, cytoscape, konva layer, autosave timer all leak

[avinxshKD]

sent #329 to fix the resize listener cleanup but that only scratched the surface. The actual leak is deeper . The actual cytoscape instance created in GraphArea.jsx - initialiseNewGraph() is never destroyed. No dispose() or destroy() method exists anywhere in the graph class chain (1-core through 6-server). When a tab closes, TabBar.jsx - closeTab() dispatches REMOVE_GRAPH, component unmounts, resize listener is removed and everything else stays alive: this.cy (full cytoscape instance + canvas + WebGL context), the Konva stage from cytoscape-node-editing, the edgehandles plugin state, and this.autoSaveIntervalId in 5-load-save.js which keeps firing setTimeout on a dead instance trying to write localStorage for a graph that no longer exists in state.

Open 10 tabs, close them, heap grows linearly, never recovers.

Fix can be, add dispose() to 1-core.js calling this.cy.destroy() + clearTimeout(this.autoSaveIntervalId) + null out refs. Call it from the useEffect cleanup in GraphArea.jsx alongside the existing resize unbind. Optionally also from closeTab() in TabBar.jsx before dispatching REMOVE_GRAPH.

[avinxshKD]

@pradeeban going to pick this up, already have the graph class chain open from the #329 work so context is fresh. will start with dispose() in 1-core.js and wire it up through the useEffect cleanup, then check if TabBar needs an explicit call too or if unmount handles it cleanly. should know in a day or two.

let me know if this makes sense

[pradeeban]

@avinxshKD ok, go for it.

[avinxshKD]

@pradeeban on it.