TSSIM/JESIM final v39 - advanced node tune box selection

Base: v38 fault-width-km clean complete build.

New feature:
- In advanced source-node fine tuning mode (E), hold Shift and drag with the left mouse button to draw a rectangle.
- On release, every source node whose marker center is inside the rectangle is added to the current selection.
- This is additive selection: existing selected nodes stay selected.
- A tiny Shift-click still behaves like the old Shift-click add-one-node action.

Existing node tune controls remain:
- E: toggle advanced node tune mode
- Click: select one node
- Ctrl-click: toggle one node
- Shift-click: add one node
- Shift-drag: add all nodes in a rectangle
- A: select all
- C or Esc: clear selection
- Tab / Shift+Tab: change primary node
- Delete / Backspace: remove selected nodes
- + / -, [ / ], PgUp/PgDn, arrows, F, U: apply edits to all selected nodes

Unchanged from v38:
- Fault width is controlled in real down-dip km.
- Already painted nodes keep their paint-time dip and moment-area factor.
- Subsidence nodes keep slip_m=0; land subsidence nodes are excluded.
- JESIM observation reports are 5-minute batches for all arrived observations.
- packet_meaningful_update is packet-wide; per-observation peak update is represented by rise.
- Shimizu is removed.
- JESIM transmit-only mode stops simulation at 60h.
- External wall-clock 1x observation timing.
- No y-axis flip.
