feat(line): add ridgeline as a Line variant (#143)

* feat(line): add ridgeline as a Line variant

One distribution per series, stacked at a fixed pitch on a single shared
amplitude. Ships three static examples (light, dark, full editorial),
the type-line.md spec, and a geometric gate.

verify-ridgeline.py derives the figure's one amplitude and its baseline
pitch from the figure itself, then holds every vertex to both. It also
checks the drawn baseline rules, the shared bin scale, absolute M/L/Z
only, the overlap ceiling, the focus pairing and every label binding.
test-verify-ridgeline.py proves each check in both polarities and pins
the scope treaty with the sibling Line gates.

The contract binds data-bins on a <path>, which no other chart in the
repo declares, so verify-slopegraph and this gate never claim the same
file.

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

* fix(verify-ridgeline): read exponent coordinates as numbers, not commands

parse_d scanned for [A-Za-z] independently of the numbers, so the `e` in a
valid scientific-notation coordinate such as 4.4e2 was counted as a path
command. The explicit-command rule then rejected a correct ridgeline with a
message about command counts.

Tokenise the d attribute left to right with the number branch tried first,
so an exponent is consumed as part of its number. A letter that survives
that branch is a real command and still faces the M/L/Z vocabulary check;
anything else leaves the path unreadable, which stays a finding.

Adds both polarities: a shipped coordinate rewritten as 4.4e2 must verify,
and a falsified one written the same way must not.

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

---------

Co-authored-by: 0xDarkMatter <0xDarkMatter@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

.factory-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "diagram-design",
   "description": "Create branded architecture, IT current-state, flowchart, sequence, state machine, ER/data model, timeline, swimlane, quadrant, radar/spider, polar chart (polar/radial lollipop), loop/flywheel, nested, tree, org chart, layer stack, Venn, pyramid/funnel, treemap, bar, line, Gantt and scatter charts, high-level, process, medallion, data flow, DP integration, DP security matrix, sankey, fishbone, Wardley map, kanban, user journey, deployment, dependency graph, UML class, story map, or database schema diagrams as standalone HTML/SVG/PNG. Redraw .drawio/.drawio.png/.drawio.svg or Mermaid .mmd sources at a chosen size/detail; onboard brand tokens from a website; add semantic patterns, callouts, accessible motion, or sketchy/hand-drawn styling.",
-  "version": "2.6.1",
+  "version": "2.6.2",
   "author": {
     "name": "Cathryn Lavery",
     "url": "https://github.com/cathrynlavery"