feat(blocks): add Wave B WordPress query and list content blocks

[TheAggressive]

Parent roadmap: #95

Outcome

CampaignBridge can build deterministic multi-post email compositions from bounded WordPress queries while preserving the immutable snapshot model established by #69 / PR #94.

Scope

• campaignbridge/post-query — select/filter a bounded ordered collection of posts/pages/CPTs.
• campaignbridge/post-list — render only the immutable result of a Post Query through a deterministic item template.
• Patterns over existing primitives for featured article, latest posts, category digest, event listing, and author digest.

Architecture

• Query execution belongs to repository/workflow boundaries, never renderers.
• Compilation consumes frozen normalized snapshots only.
• Define explicit max item count/query budget.
• Define deterministic ordering and empty-result policy.
• Reuse the existing campaignbridge/post-data semantics for individual item fields where possible.
• Do not add one renderer per post type.
• Do not let a live query run during compile or preview of an approved snapshot.

Required evidence

• Same query snapshot + template + design => identical artifact.
• Source edits after snapshot do not mutate reviewed output.
• Empty, deleted, private, or inaccessible results fail/behave according to one documented policy.
• Query limits are enforced before expensive work.
• Editor, compiler, and snapshot field requirements remain contract-aligned.

Closeout

Close when bounded multi-post content can be authored, snapshotted, compiled, and tested without any live-content read inside renderers.