Time estimator fixes (#15304)

* Plan corners with junction deviation where the firmware uses it

The time estimator only ever had the classic per-axis jerk model, which limits a
corner by the largest single-axis component of the velocity change. That is
anisotropic: the same corner is allowed sqrt(2) more speed on a diagonal than on
an axis, which paints a four-lobed ripple around every circular wall in the
actual speed and actual flow views, worst on small parts whose walls are made of
short segments.

Klipper has no classic jerk at all and Marlin 2 has none while M205 J is in use;
both plan corners with junction deviation, which sees only the corner angle. Add
that model and use it for those machines:

  - Klipper: derived from the square corner velocity, as the firmware does
    (jd = scv^2 * (sqrt(2) - 1) / max_accel), reading the scv from
    machine_max_jerk_x, where process_SET_VELOCITY_LIMIT() already stores
    SQUARE_CORNER_VELOCITY.
  - Marlin 2: machine_max_junction_deviation, which was already loaded into the
    machine limits but never reached the planner.
  - Every other flavor keeps the classic jerk path unchanged.

The model has no per-axis jerk floor, so this also drops the hard slow spot the
estimator drew at the start of every loop from machine_max_jerk_e.

Toolpaths are unaffected: on a full export the only lines that change are M73.

The junction deviation maths, including Marlin's JD_HANDLE_SMALL_SEGMENTS arc
approximation, is ported from PrusaSlicer's src/libslic3r/GCode/GCodeProcessor.cpp.
The Klipper mapping is not in PrusaSlicer, which ignores SET_VELOCITY_LIMIT.

* Add tests for junction deviation corner planning

Cover the three properties the change rests on:

  - a right angle on Klipper is planned at exactly the square corner velocity,
    the identity that makes the scv to junction deviation mapping correct, and a
    shallow corner is planned far faster than per-axis jerk allows;
  - junction deviation gives the same speed whatever the corner's orientation,
    while classic jerk keeps its sqrt(2) spread, which is the four-lobed ripple;
  - machines that do not plan with junction deviation are provably untouched,
    including a Marlin 2 printer that has it disabled.

src/libslic3r/GCode/GCodeProcessor.hpp

@@ -637,6 +637,10 @@ class Print;
                 //For line move, there are same. For arc move, there are different.
                 Vec3f enter_direction;
                 Vec3f exit_direction;
+                // Orca: move direction over all four axes, scaled by 1 / block.distance. Used by
+                // calc_vmax_junction_deviation(), which needs E to see extrusion-rate changes
+                // between collinear moves the way Marlin and Klipper do.
+                Vec4f jd_unit_vec;
 
                 void reset();
             };
@@ -1488,6 +1492,16 @@ class Print;
         float get_axis_max_acceleration(PrintEstimatedStatistics::ETimeMode mode, Axis axis, int machine_idx) const;
         float get_axis_max_jerk_with_jd(PrintEstimatedStatistics::ETimeMode mode, Axis axis, float acceleration) const;
         float get_axis_max_jerk_with_jd(PrintEstimatedStatistics::ETimeMode mode, Axis axis) const;
+        // Orca: junction deviation for a block at the given acceleration, 0 for a classic jerk machine.
+        float get_junction_deviation(PrintEstimatedStatistics::ETimeMode mode, float acceleration) const;
+        // Orca: acceleration along the junction direction, clamped by the per axis limits.
+        float calc_junction_acceleration(const TimeBlock& block, const Vec4f& junction_unit_vec,
+                                         PrintEstimatedStatistics::ETimeMode mode) const;
+        // Orca: entry speed from the junction deviation model, which limits a corner by its angle alone
+        // and is therefore isotropic, unlike per axis jerk. Negative means classic jerk applies instead.
+        float calc_vmax_junction_deviation(const TimeBlock& block, const TimeMachine::State& prev,
+                                           const TimeMachine::State& curr, bool has_prev_move,
+                                           PrintEstimatedStatistics::ETimeMode mode) const;
         float get_axis_max_jerk(PrintEstimatedStatistics::ETimeMode mode, Axis axis) const;
         Vec3f get_xyz_max_jerk(PrintEstimatedStatistics::ETimeMode mode) const;
         float get_retract_acceleration(PrintEstimatedStatistics::ETimeMode mode) const;