[Agent] Search changelog URLs use broken hash anchors

Agent brief

Category: bug | Severity: medium | Effort: XS

Problem

Changelog search hits link to /{slug}/changelog#${entry.slug} but real URLs are /{slug}/changelog/${slug}. Hash anchors do not exist on index page.

Repro

1. Search palette → pick a changelog hit
2. Lands on changelog index with hash that does nothing

Files

• src/app/api/search/route.ts line ~205

Acceptance criteria

• Changelog search URLs match changelog/[slug]/page.tsx routes
• Click navigates to correct entry page

Suggested approach

Change to /${c.project.slug}/changelog/${c.slug}.