TSSIM/JESIM v44 - finite-fault stamp nearest-connection update

Change:
- In finite-fault stamp mode, new patches are no longer bridged only from the immediately previous stamp.
- When a patch is clicked inside the same open fault, the program scans existing patch centers in that fault_id and connects from the nearest existing patch center to the new patch.
- Bridge patches inserted between stamps are also real patch centers, so later clicks can connect to the closest bridge/patch rather than forcing a zig-zag through the last clicked point.

Why:
- For large earthquakes, users often fill the fault in blocks or rows. Connecting only to the last clicked patch can create unnecessary long diagonal bridges.
- Nearest-patch connection makes the stamp workflow behave more like filling a continuous finite-fault surface.

Kept from v43:
- Ctrl+Z undo
- stamp width changes keep aspect ratio
- stamp delay control
- finite-fault stamp mode
- advanced node tune multi/box selection
- JESIM 5-minute packets and packet_meaningful_update
- Shimizu removed
- external wall-clock 1x
- no axis flip
