Add conditional styling override for nodes and edges

[jkemmererupgrade]

Description

Slice 3 of the 3-slice split of aws#1589, stacking on Slice 2 (#3).

Adds per-type conditional style overrides to vertices and edges. When a node or edge's source property matches a configured condition (property operator value), a secondary style (color, icon, border, shape, opacity, display properties) overrides the base style in the graph canvas and all previews.

Architecture

• StyleCondition type + buildConditionalNodeSelector/buildConditionalEdgeSelector helpers in conditionalStyling.ts
• condition + conditionalStyle fields on VertexPreferencesStorageModel / EdgePreferencesStorageModel (optional, excluded from the required VertexPreferences runtime type)
• renderedEntities.ts flattens vertex.original.attributes into Cytoscape element data as prop_<key> entries so Cytoscape selectors can match them. Date values are coerced to ISO strings for lexicographic comparison.
• useGraphStyles.ts emits additional high-specificity selectors (node[type="X"][prop_known_bad = "true"]) for types that have a condition + conditionalStyle set
• useBackgroundImageMap.ts generates conditional icon queries keyed as ${type}:cond
• NodeStyleDialog and EdgeStyleDialog gain a Base / Conditional tab toggle. The conditional tab shows a condition builder (ConditionalSection component: property dropdown from schema, operator select filtered by dataType, value input) and a full copy of the style fields wired to conditionalStyle. Selecting a property shows a VertexSymbol preview of the node with the conditional style applied.
• The styling file format (Zod schema in defaultStyling.ts) accepts condition + conditionalStyle — round-trips cleanly through import and export

Supported operators

DataType	Operators
String, Boolean	=, !=
Number, Date	=, !=, >, <, >=, <=

Date values from Neptune are coerced to ISO 8601 strings; comparisons work lexicographically (e.g. create_date > 2026-03-26).

Deliberately NOT in this PR

• No changes to Slice 1 (icon picker) or Slice 2 (import/export UI) behavior

Validation

• pnpm run checks — lint + format + types clean
• pnpm test — 1813 / 1813 pass
• pnpm coverage — all 4 thresholds met
• Manually validated against live Neptune backend: conditional color + icon override applied to matching nodes; non-matching nodes kept base style; date comparison works with ISO format; per-type Remove Condition restores base; import/export round-trips condition + conditionalStyle

Related Issues

• Slice 3 of Add defaultStyling.json support for persistent per-type vertex and edge styling aws/graph-explorer#1589
• Stacks on Add styling import / export / reset UI #3 (Slice 2)

Check List

• I confirm that my contribution is made under the terms of the Apache 2.0 license.
• I have verified pnpm checks passes with no errors.
• I have verified pnpm test passes with no failures.
• I have covered new added functionality with unit tests if necessary.
• I have updated documentation if necessary (docs/features/graph-view.md).