unic-spec-review S5: page traversal — child pages + in-body /wiki/ links via traversal-planner with budget gate

[orioltf]

Parent

Epic: #200 — unic-spec-review plugin.

What to build

Expand the review from one pasted page to the whole spec, under an explicit budget gate. Add traversal-planner: given seed pages plus fetched page metadata (child pages and in-body /wiki/ links), it produces an expansion plan and a budget-gate decision.

Behaviour:

• Discover child pages of each seed and in-body links to other Confluence pages (so related pages outside the parent-child tree are not missed).
• Before a large or expanding fetch, show the reviewer the discovered page set and count and ask them to confirm or trim. The review stays bounded and the reviewer controls the cost.
• The confirmed set is then fetched and fed to the review engine.

Still read-only.

Acceptance criteria

• traversal-planner takes seeds + page metadata (child pages, in-body /wiki/ links) and produces an ordered expansion plan with a budget-gate decision.
• Child pages of seeds and in-body Confluence links are both discovered and included in the candidate set.
• Before a large/expanding fetch, the discovered page set and count are shown and the reviewer can confirm or trim before any bulk fetch happens.
• The confirmed page set is fetched and reviewed; the run remains read-only.
• node:test unit tests cover traversal-planner (expansion + budget-gate logic) with injected page metadata; no live services.
• PR adds CHANGELOG.md bullets under [Unreleased] and bumps the patch version; verify:changelog passes. No em dash in authored text (except the mandated CHANGELOG version header).

Blocked by

• unic-spec-review S1: skeleton tracer bullet — classify one URL, fetch page, one Gaps agent, write report #202 (S1 — page fetch + classifier).
• unic-spec-review S3: shared context — read existing comments + Landscape Brief #204 (S3 — multi-page context/comment read the traversal feeds into).