perf: speed up .apply_modifiers() in make.R

[Copilot]

Removes the ## TODO: speed this up comments in .apply_modifiers() by implementing the actual speedups.

Changes

• without_attr: Replace three O(N) loops (get names → delete one-by-one) with three direct bulk assignments to structure(list(), names = character(0)) — O(1) regardless of attribute count.
• with_vertex_ / with_edge_: Replace per-attribute set_vertex_attr/set_edge_attr calls (each doing a full C-level get+modify+set cycle) with a single get → in-memory loop with scalar recycling and length validation → single set. Reduces from N get+set pairs to 1 get + 1 set. Error messages correctly report make_() as the call context via the call parameter.
• with_graph_: Replace per-attribute loop with the existing modify_list() helper + graph.attributes<- for a single get+set cycle.
• Add snapshot tests for wrong-length attribute value errors in with_vertex_() and with_edge_().

• By submitting this pull request, I assign the copyright of my contribution to The igraph development team.

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[krlmlr]

@copilot: Resolve conflicts and run tests, fix as needed.

[Copilot]

@copilot: Resolve conflicts and run tests, fix as needed.

Merged main, resolved conflicts, and fixed the CI failure (commit 7adb10e). The check was reporting NOTEs for setNames (from stats) and modifyList (from utils) not being imported. Replaced them with structure(list(), names = character(0)) and the existing modify_list() helper respectively.

[krlmlr]

@copilot: Ensure this can be merged cleanly into main. The previous attempt still produces a branch with conflicts.

[Copilot]

@copilot: Ensure this can be merged cleanly into main. The previous attempt still produces a branch with conflicts.

Merged main cleanly in d35b162. The conflicts were in R/make.R and the snapshot file — resolved by combining our performance improvements with main's call parameter propagation (so errors now correctly report make_() instead of .apply_modifiers()).