[LeadcodeDev]

Closes #433. Part of #438.

Waypoints without a click. A path waypoint clicked on arrival with no way to
opt out, so a pointer could not round a corner on its way to the control a
walkthrough is about. CursorWaypoint gains click, defaulting to true, so
every scenario written before it renders identically. click_at stays ignored
while a path is present — clicks_come_from_the_waypoints_when_a_path_is_given
pins that contract, and a first attempt at chaining the two turned it red. A
pointer that should click somewhere says so on the waypoint.

The glyphs. The hand was an open heptagon plus a detached triangle; the fist
was a bare heptagon. The polygon was never the real limit — add_contour only
emits line_to, so no sequence of points was going to read as a hand.
add_smooth_contour runs a quadratic through the midpoint of each edge, and that
is what turned a blob into a palm. The arrow keeps its hard corners.

The finger also had to survive the glyph's own outline stroke. At size * 0.07
centred on the path it eats size * 0.035 inward on each side, so a finger 14 px
wide in the polygon painted 6 px of fill — measured, after three iterations that
each looked right in the source and wrong in the frame. A blunt tip rather than a
tapered one is what finger_probe was already asking for at (0.08, 0.05).

tone: "outline". A white stroke over a transparent fill, so on a white frame
it was invisible — while its own doc comment promised it reads on any background.
Making the code match the promise beat deleting the promise: the glyph now carries
a dark contour under the white one. Declaring outline_color turns the contour
off, since at that point you have said what the edge should be.

Tests

a_waypoint_can_be_passed_through_without_clicking,
a_waypoint_clicks_by_default_so_an_existing_scenario_is_unchanged,
opting_every_waypoint_out_leaves_a_pointer_that_travels_and_never_clicks, and
an_outline_pointer_carries_a_dark_contour_so_it_reads_on_a_light_frame, which
scans the whole frame for the darkest painted channel.

The existing hand_glyph_closes_into_a_grab_during_a_click_and_reopens_after and
finger_probe_is_inside_the_open_hand_but_outside_the_closed_fist both constrain
the redraw and both stayed green.

cargo test -p rustmotion-components --lib pointer 19 passed. Clippy and the full
suite run at integration — two sibling workstreams are mid-flight in this checkout.