feat(units): read back every form the drawing writes

The readout learned to write lengths as 5'-6 1/2" and angles as
N 45d0'0" E, but typed input was still a bare parse::<f64>() — a
coordinate could be displayed and not entered. Give the formatters
their inverses.

parse_length takes feet and inches separated by a dash, a space, or
nothing, with the closing quote optional, and whole-plus-fraction in
any of those forms: 5', 60", 5'-9", 5'9-1/2, 9-1/2, 1/2. A leading
minus is a sign; the one inside 5'-9" is a separator, since after feet
there is nothing left to subtract from.

parse_angle reads the mark that says which convention an angle is in —
g for grads, r for radians, d/'/" for degrees-minutes-seconds, compass
letters for a surveyor's bearing — and reads a bare number in whichever
convention the drawing is set to.

ANGBASE and ANGDIR now apply, but only where they mean something. Which
way a thing points is measured from the drawing's zero and runs the way
it says; how wide an arc opens is the same number whatever zero is
counted from. format_direction and parse_direction are the pair for
directions, and the polar readout and polar input both go through them,
so the bearing shown is the bearing accepted. format_angle stays for
sizes, where applying a base angle would corrupt the value.

The command prompts follow the same rule, each classified rather than
swept: OFFSET distance, FILLET radius, CHAMFER distances, ARRAY and
MINSERT spacing, TRACE width, HELIX, and EXTRUDE height read lengths;
the four dimension text-rotation prompts, ARRAY's total angle and
INSERT's rotation read angles. MLINE's scale and INSERT's scale factor
are left alone — a multiplier has no unit to be written in. INSERT read
both through one parse; they are now separate.

The typed variants also take a decimal comma, which a single-value
prompt has no other use for. parse_length itself does not: inside a
coordinate the comma separates the axes.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/modules/insert/insert_block.rs

@@ -220,16 +220,24 @@ impl CadCommand for InsertBlockCommand {
             }
             Step::FillAttr { .. } => Some(self.accept_attr_value(text)),
             Step::Point { .. } => {
-                // Typing the value awaited after a Scale / Rotate keyword.
+                // Typing the value awaited after a Scale / Rotate keyword. The
+                // two read differently: a scale is a plain multiplier with no
+                // unit to write it in, while a rotation is an angle and takes
+                // whichever convention the drawing is set to.
                 if let Some(kind) = self.awaiting {
-                    if let Ok(v) = text.trim().parse::<f64>() {
-                        match kind {
-                            AwaitKind::Scale if v != 0.0 => {
-                                self.x_scale = v;
-                                self.y_scale = v;
+                    match kind {
+                        AwaitKind::Scale => {
+                            if let Ok(v) = text.trim().parse::<f64>() {
+                                if v != 0.0 {
+                                    self.x_scale = v;
+                                    self.y_scale = v;
+                                }
+                            }
+                        }
+                        AwaitKind::Rotation => {
+                            if let Some(v) = crate::entities::common::parse_typed_angle(text) {
+                                self.rotation_rad = v;
                             }
-                            AwaitKind::Scale => {}
-                            AwaitKind::Rotation => self.rotation_rad = v.to_radians(),
                         }
                     }
                     self.awaiting = None;

src/modules/insert/minsert.rs

@@ -228,12 +228,12 @@ impl CadCommand for MinsertCommand {
                             }
                         }
                         ParamIdx::RowSpacing => {
-                            if let Ok(v) = typed.parse::<f64>() {
+                            if let Some(v) = crate::entities::common::parse_typed_length(typed) {
                                 self.row_spacing = v;
                             }
                         }
                         ParamIdx::ColumnSpacing => {
-                            if let Ok(v) = typed.parse::<f64>() {
+                            if let Some(v) = crate::entities::common::parse_typed_length(typed) {
                                 self.column_spacing = v;
                             }
                         }

src/modules/insert/solid3d_cmds.rs

@@ -77,9 +77,7 @@ impl CadCommand for ExtrudeCommand {
         self.step == ExtrudeStep::Height
     }
     fn on_text_input(&mut self, text: &str) -> Option<CmdResult> {
-        text.trim()
-            .parse::<f64>()
-            .ok()
+        crate::entities::common::parse_typed_length(text)
             .filter(|&h| h.abs() > 1e-6)
             .map(|h| CmdResult::ExtrudeEntity {
                 handle: self.target_handle,