Pencil: Fidelity keeps its screen size at low zoom

The Pencil and the Paintbrush send their Fidelity in points at the
current zoom, but path.freehand read at most 100 pt. At 3.13% zoom a
20 px Fidelity (639 pt) was fitted at 100 pt, the same as 3.13 px on
screen, so a stroke drawn zoomed out kept far more anchors than the
same stroke at 100%.

- path.freehand, and brush.freehand, which runs it, take a Fidelity
  from MIN_FIT_TOLERANCE to MAX_FIT_TOLERANCE (100 / 0.0313 pt, the
  100 px field maximum at the lowest zoom). A value outside that range
  is now rejected with an error instead of being read as the nearer
  end. The default stays 1.5 pt and path.blob keeps its 100 pt bound.
- The Pencil and the Paintbrush keep the value they send within that
  range, so a stroke draws at any zoom.
- An extending stroke still closes the path within four Fidelities of
  its other end, at most 400 pt, as before.

It conflicts with open #7089 in crates/tools/src/draw2.rs.

Docs: docs/mcp.md, docs/target-app-parity.md, path.freehand params.

docs/mcp.md

@@ -2916,6 +2916,13 @@ already walks Image Trace. Short agent entry points:
   Tilt goes from its first value with the pen lying flat to its second upright, and on Bearing or Rotation from its
   first value at −180° to its second at 180°. A stroke without that input draws the brush's own value (a Scatter
   brush's value half way between the two).
+- Freehand Fidelity: the `fidelity` of `path.freehand` and `brush.freehand` is in points, 1.5 pt when left out. A
+  value must be from 0.000015625 pt (0.01 / 640) to 100 / 0.0313 pt (about 3194.89 pt), and a value outside that range
+  is rejected with an error. The Pencil and the Paintbrush give Fidelity in screen pixels, 0.01 to 100 px, and send it
+  divided by the zoom (0.0313 to 640) and kept within that range, so a stroke is fitted at the same tolerance on screen
+  at every zoom. A stroke
+  that continues a path (`extend`) closes it when it ends within four times the Fidelity of the path's other end, at
+  least 6 pt and at most 400 pt. The Blob Brush's `path.blob` Fidelity stays in points, 0.01 to 100 pt.
 - Variables: `variable.list`, `variable.define {name, kind: text|visibility|image|graph}`, `variable.bind {variable, ids?}`,
   `variable.makeTextDynamic`, `variable.makeVisibilityDynamic`, `variable.makeImageDynamic`, `variable.makeGraphDynamic`
   (`variable.bind` and `variable.makeTextDynamic` refuse type that already has another text variable and name it),

docs/target-app-parity.md

@@ -1086,6 +1086,7 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
     Live curve fitting in the Pencil Tool Options is on by default; while it is off, the path shown while a stroke is drawn joins the stroke's points with straight segments, and the release fits the curve, as [Pencil Tool Options](https://web.archive.org/web/20261002104400/https://helpx.adobe.com/illustrator/desktop/draw-shapes-and-paths/draw-shapes/pencil-tool-options.html) describes (`path.freehand` `fit`).
     In the Pencil and Paintbrush Tool Options, Edit selected paths within 0 px turns editing off, so a stroke that starts exactly on an end of a selected open path draws a new path; Close paths when ends are within 0 px turns closing off, so a stroke that ends exactly where it started stays open.
     The Pencil's and the Paintbrush's Fidelity is in screen pixels, the same at any zoom: their Tool Options give it in px, from 0.01 px on the logarithmic slider to 20 px and up to 100 px in the field, and the tool sends `path.freehand` the value in points at the current zoom (#5729). The Smooth tool's and the Blob Brush's Fidelity stays in points.
+    `path.freehand` and `brush.freehand` take a Fidelity of up to 100 / 0.0313 pt (about 3194.89 pt), the 100 px field maximum at the lowest zoom (3.13 %), and reject a value outside their range with an error, so a Pencil or Paintbrush stroke drawn zoomed out keeps the Fidelity set in pixels (engine tests `pencil_fit_keeps_its_anchors_on_a_stroke_drawn_zoomed_out` and `pencil_takes_fidelity_within_its_range_and_rejects_the_rest`).
     Before a press that draws a new path, the Pencil cursor shows a small star, as [Draw freeform paths with the Pencil tool](https://web.archive.org/web/20260926095638/https://helpx.adobe.com/illustrator/desktop/draw-shapes-and-paths/draw-shapes/draw-freeform-paths-with-the-pencil-tool.html) describes; over a selected path within Edit selected paths' distance, which the press continues from an end or redraws, the star is not shown ([Reshape paths with the Pencil tool](https://web.archive.org/web/20260106004407/https://helpx.adobe.com/illustrator/desktop/draw-shapes-and-paths/draw-shapes/reshape-paths-with-the-pencil-tool.html)).
     Keep selected in the Pencil and Paintbrush Tool Options is on by default: while it is on, a stroke selects the path it draws or continues and replaces the earlier selection. While it is off, a new stroke leaves nothing selected, the earlier selection included, as the reference application starts the stroke by dropping it (#5752); a continued or redrawn path is deselected while the rest of the selection stays (`path.freehand` `keepSelected`).
     With two open paths selected, a Pencil stroke from an end of one that ends within Edit selected paths' distance of an end of the other connects them into one path with the first path's appearance, in one undo step, as [Connect two paths with the Pencil tool](https://helpx.adobe.com/illustrator/desktop/draw-shapes-and-paths/draw-shapes/connect-two-paths-with-the-pencil-tool.html) describes (`path.freehand` `connect`).