Simulate the corner blocks and goal line boundary of the SSL field

[Andrewyx]

Description

WIP Claude Template

Third of four stacked PRs porting upstream ER-Force simulator changes (#3912). Stacked on #3948.

Ports the field collider changes upstream made for the newer SSL field layouts (upstream 74afb1f4, d496e5ff, 48245210, c002db2f, db1fddb0):

• Corner blocks: the triangular blocks that smooth out the corners of the field, which real SSL fields have had since 2023. Both of our field configs now declare them (corner_block_cathetus_length: 0.09), so a ball rolled into a corner is deflected instead of coming to rest in the corner itself.
• boundary_width_goal_line, for fields whose boundary behind the goal lines is wider than the one along the touch lines. It falls back to boundary_width, so our fields keep their walls exactly where they are; the side walls of the goals now extend back to the wall.
• A mode for playing without any boundary area at all, where the goals stand outside the field lines and the wall behind the goal line is split around them. Unused by our configs, ported so we are ready for it.

The three new geometry fields are added to the simulator's world.proto and to our SSL_GeometryFieldSize, using the field numbers from the official SSL Vision protocol so we stay wire compatible with real vision. Field keeps its single boundary_buffer_size for now — a non uniform boundary there belongs with adopting the 2026 field dimensions, which this PR deliberately does not do (the sim still loads the 2020 configs).

One behaviour change to flag: porting upstream's goal placement also shifts the goals outward by half a line width (5 mm). That is what upstream's code does; note that their comment says the opposite of their code, so this is worth a second opinion.

Testing Done

• New er_force_simulator_test case: a ball driven into a field corner never enters the cut off corner triangle. Verified it is a real guard by removing corner_block_cathetus_length from the config, where the ball reaches 0.035 m from the corner against the 0.0675 m threshold.
• ssl_geometry_test and the existing field configuration tests pass, i.e. the geometry round trip is unchanged when the new fields are absent.
• Same full suite runs as Fix ER-Force simulator dribbling physics and reported ball model #3947.

Resolved Issues

Part of #3912

Length Justification and Key Files to Review

247 lines. Key file: src/extlibs/er_force_sim/src/amun/simulator/simfield.cpp.

Review Checklist

• Function & Class comments
• Remove all commented out code
• Remove extra print statements
• Resolve all TODO's