fix(knowledge-graph): code-review fixes for 3D view toggle (#3330)

[mrveiss]

Summary

Follow-up fixes from code review of PR #3359 (feat: 3D knowledge graph toggle):

• Memory leak (bug(knowledge-graph): Three.js GPU resources not disposed on KnowledgeGraph3D unmount #3399): Add full Three.js GPU resource disposal in `onUnmounted` — traverses scene tree, disposes geometry, materials, and textures before calling `renderer().dispose()`
• ResizeObserver (fix(knowledge-graph): KnowledgeGraph3D canvas does not resize when container dimensions change #3370): Resize the WebGL canvas when container dimensions change (e.g. when the entity details panel opens/closes)
• Blank 2D canvas (bug(knowledge-graph): Cytoscape canvas blank after toggling from 3D back to 2D #3400): Double `nextTick` in `toggleViewMode` so Cytoscape has time to re-initialize after `v-if` flips back to 2D
• i18n (bug(knowledge-graph): 3D/2D toggle button labels hardcoded in English, not i18n #3401): Replace hardcoded `"3D"` / `"2D"` toggle button strings with `$t()` keys in all 11 locale files

Test plan

• Toggle 2D→3D→2D repeatedly; Cytoscape should render correctly on return
• Open entity details panel while in 3D; canvas should resize to fill remaining space
• Toggle 3D on and off many times; check browser memory profile shows no GPU leak
• Verify toggle button tooltip text appears in all supported locales

Closes #3330
Closes #3370
Closes #3399
Closes #3400
Closes #3401

🤖 Generated with Claude Code

[mrveiss]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

🤖 Generated with Claude Code

[mrveiss]

Closing: both commits in this PR were already applied to Dev_new_gui via PRs #3369, #3410, #3411, and #3412. After rebasing, the branch has no diff from the base — the fixes this PR intended are all present on the main branch.