Fix simple filled icons: single fill-only path, no stroke overlay

SF Symbol template rendering exposes all paths — the stroke overlay's
inner contour was showing as a visible outline. Simple filled icons
(heart, heart-rounded, bookmark, grid01) now use a single path with
fill="black" stroke="none" to produce one clean glyph per weight.

Lock and home overrides unchanged (working correctly as-is).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: lcandy2