⚡ Bolt: Optimize graph edge iteration for PageRank and HITS

[saurabhsharma2u]

💡 What: Added a memory-efficient forEachEdge iterator to the Graph class and updated the PageRankService and HITSService algorithms to use it instead of calling graph.getEdges().

🎯 Why: Calling graph.getEdges() inside these algorithm setups was previously mapping every single edge in the graph.edges Map to a new { source, target, weight } object array. This massive spike in array object allocations immediately before memory-heavy typed array allocations led to severe Garbage Collection pressure and performance degradation. Exposing forEachEdge performs inline parsing of the composite string key delimiter (\x00) and passes scalar arguments (strings/numbers) straight to the callback without intermediate object allocations, safely maintaining the underlying encapsulation of the Graph class.

📊 Impact: Reduces array memory allocation and Garbage Collection spikes for large graph processing, visibly improving execution speed during metrics calculations without any regression to functionality or architectural boundaries.

🔬 Measurement: Verified the improvement by running large-scale graph tests using Vitest (e.g. pnpm test tests/pagerank_perf_large.test.ts and tests/hits_perf_large.test.ts), which executed significantly faster. All pnpm test cases pass.

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PR created automatically by Jules for task 15909475517467732390 started by @saurabhsharma2u

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