Article entries in the CP path list now show the article label
(letter/extension) instead of just "article", with a property count
in the meta column. In the FO pane, each property is rendered as an
editable row: key input, value input (coerced via ast-parser.coerce),
scope toggle, morphing default/overwrite label, and per-row remove
button. A "+ add property" button appends a blank defaults entry.
Every edit marks the score dirty.
`coerce` is now exported from ast-parser.js so the FO pane can apply
the same type-inference rules to user input as the parser does to
AST values.
Previous commit took the user's (O-) / (-O) shorthand literally and put
those glyphs as the button label. They were describing the visual states
of a real toggle switch, not text to display.
Now: pill-shaped track with a sliding circular thumb, "default" and
"overwrite" labels flanking it (the active side brightens). The button
carries role="switch" + aria-checked for accessibility. Click anywhere
on the track to flip and mark the score dirty.
