Waveform debugger breakpoints: whole change-list loading silently caps out on busy signals; search with windowed edge/search queries

In a waveform-viewer debugger (an FSDB/VCD-backed 'step through the simulation' UI), stepping and value display scaled fine on a large SoC dump. Breakpoints and conditions, however, worked by loading each watched signal's full change list, capped at 1M changes, and skipped any breakpoint over the cap with a warning. A PC register had 1.33M changes and a 512-bit bus had 6.5M, so the most useful breakpoints (PC == addr, PC is X) would be skipped on exactly the designs where you need them. A small course design never hit the cap, so it looked fine in daily use. Lessons: (1) a 'debugger works on FSDB' smoke test that only steps doesn't cover breakpoints, conditions or reverse; test each feature on a large real dump; (2) break and condition search should ask the backend for the next or previous matching edge in a window (an edge/search API) rather than materialise every change; (3) when a cap does apply, surface it on the breakpoint itself, not as a one-off console warning.