Add fast trap_burden mode with lightweight bulk/original-basis computation

[charlesmartin14]

Motivation

• Provide a lightweight "fast" mode for trap burden analysis optimized for ablation/sweep scenarios to avoid expensive original-basis diagnostics and full bulk reconstruction loops.
• Avoid redundant SVD work by allowing reuse of a precomputed SVD when identifying and analyzing trap modes.
• Make trap analysis behavior configurable so callers can choose between full diagnostics and a faster approximate path.

Description

• Added a trap_burden_mode argument (default "full") and flags compute_original_basis, compute_full_bulk_reference, bulk_mode_sample, and compute_original_trap_svd to analyze_traps interfaces in both weightwatcher.analyze_traps and trap_analysis.analyze_traps and wired defaults so "fast" disables expensive work.
• Changed remove_traps.identify_trap_mode_indices to accept optional svals to avoid recomputing the SVD when available.
• Added compute_fast_bulk_trap_reference_metrics which computes bulk-mode statistics from precomputed U,S,Vh (with optional sampling) to replace full bulk reconstruction in fast mode.
• Modified apply_analyze_traps to optionally skip compute_original_basis_for_traps, precompute the permuted SVD once, call identify_trap_mode_indices with svals, and conditionally call the fast or full bulk metric functions.
• Enhanced analyze_single_trap to accept a precomputed_svd and a compute_original_trap_svd toggle so the method can avoid extra SVDs and fall back to permuted-mode-derived metrics when the original basis is not computed.
• When the original basis is unavailable, fallback computations for overlap statistics use the permuted singular values to populate ov_* fields and several new output columns were added: B_absDelta_ipr_ovlamvar, B_absDelta_logtop5_ovlamvar, B_evalsq_logtop5_ovrank, and B_old_pr359_paper.
• Updated tests in tests/test_analyze_traps.py to assert that fast mode skips the original-basis and full bulk-reference computations and that full mode still provides full diagnostics.

Testing

• Ran the trap analysis unit tests with pytest tests/test_analyze_traps.py including the new tests test_analyze_traps_fast_mode_skips_original_basis, test_analyze_traps_fast_mode_skips_full_bulk_reference, and test_analyze_traps_full_mode_allows_full_diagnostics and the suite completed successfully.
• Existing trap-analysis related tests in tests/test_analyze_traps.py were executed and passed.

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