feat(array_glyph): group facet parameters — PanelLabels + figure_size

[MAfarrag]

Context

Part of the grouped render-parameter refactor (branch `refactor/grouped-render-params`, PR #274). ArrayGlyph.facet
carried two separate coordinate-label sequences and a matplotlib-style figsize.

Problem / Current Behaviour

facet took col_coords and row_coords as two parallel arguments (pushing the signature over SonarCloud's
python:S107 parameter cap), and used figsize for the shared-figure size.

Affected locations

File	Symbol	Notes
src/cleopatra/glyphs/gridded/array_glyph.py	PanelLabels (new)	bundles col / row panel-title labels
src/cleopatra/glyphs/gridded/array_glyph.py	ArrayGlyph.facet	labels=PanelLabels(...), figsize -> figure_size

Motivation Example

from cleopatra.glyphs.gridded.array_glyph import ArrayGlyph, PanelLabels
glyph.facet(col="month", labels=PanelLabels(col=["Jan", "Feb", "Mar"]), figure_size=(12, 4))

Proposed Solution

Introduce PanelLabels(col=, row=) for the per-panel titles and rename figsize -> figure_size. Drops
facet back under the S107 parameter cap.

Out of Scope

Renaming the constructor-level figsize option (shared across the Glyph base and every glyph) — deliberately
left unchanged; facet(figure_size=) is currently inconsistent with ArrayGlyph(figsize=).

Effort Estimate

Size: S
Rationale: one small object plus a parameter rename in a single method.

Definition of Done

• PanelLabels exists and facet consumes labels=
• facet uses figure_size
• tests cover titles / name_dicts / length mismatch / figure sizing
• docstrings / docs updated
• all existing tests continue to pass