Further optimise BuildAllDependsAndPaths()

[vaisest]

Description of the problem being solved:

This further optimises BuildAllDependsAndPaths() a tiny bit. In my totally realistic synthetic benchmark it made it about 1 ms faster (5.6 -> 4.6). This is done by sorting path neighbours so that the FindStartFromNode() does less work on average, and by changing the node path from an array of the whole path, to just linking to a parent node.

Steps taken to verify a working solution:

• Tests pass
• Tree behaves as expected when manually tested

Link to a build that showcases this PR:

Build used for testing: https://poe.ninja/poe1/pob/98d8f

[vaisest]

This also fixes a crash when a mastery node is on the trace path

[mcagnion]

Reproduced on 910adabc: Shift-tracing an alternative path to a mastery is silently ignored. After selecting the mastery effect, PoB allocates the default route instead of the highlighted one.

SaveMasteryPopup() only forwards viewer.tracePath when the mastery is its final node. The new hoverNode.type ~= "Mastery" guard prevents that, so AllocNode() receives nil and follows pathParent.

Enregistrement.2026-08-30.124944.mp4

AI-assisted review disclosure: This finding was identified during a review using OpenAI Codex and confirmed with a focused manual reproduction.