Build `backlog` Rune

Summary

Aggregation rune that queries the entity registry and renders a filtered, sorted, grouped view of work items and bugs. This is the first Phase 2 rune in the plan package — it requires the cross-page pipeline and entity registration (WORK-020) to function.

The backlog rune is also the rendering primitive used by the milestone auto-backlog feature (WORK-025).

Attributes

Name	Type	Default	Description
`filter`	String	—	Filter expression: `field:value` pairs (e.g., `status:ready priority:high`)
`sort`	String	`priority`	Sort order: `priority`, `status`, `id`, `assignee`, `complexity`, `milestone`
`group`	String	—	Group items by: `status`, `priority`, `assignee`, `milestone`, `type`, `tags`
`show`	String	`all`	Entity types to include: `all`, `work`, `bug`

Filter Syntax

Space-separated field:value pairs. Multiple values for the same field act as OR. Different fields act as AND.

{% backlog filter="status:ready priority:high" /%}
{% backlog filter="milestone:v0.5.0" sort="priority" group="status" /%}
{% backlog filter="assignee:bjorn status:in-progress" /%}
{% backlog filter="tags:tint" show="work" /%}

Card Layout

Each entity renders as a compact summary card showing id, status badge, priority badge, complexity dots, title, milestone, and checklist progress (if available).

Acceptance Criteria

Rune schema in runes/plan/src/tags/backlog.ts with filter/sort/group/show attributes
Filter parser handles field:value syntax with AND/OR semantics
aggregate() pipeline hook queries entity registry for work and bug entities
Results sorted by specified field
Results grouped into sections when group specified
Summary card rendering with BEM classes (rf-backlog, rf-backlog__card, etc.)
Engine config in runes/plan/src/config.ts
CSS in packages/lumina/styles/runes/backlog.css
Tests for filter parsing, sorting, grouping, and card rendering
Type definition in runes/plan/src/types.ts
Exported from runes/plan/src/index.ts

Dependencies

WORK-020 (entity registration) must be complete first
Uses PackagePipelineHooks.aggregate() from @refrakt-md/types