fix(cli): #1715 split active content keys on first hyphen so hyphenated collections resolve

[jstockdi]

Related Issue

Resolves #1715

Documentation

N/A — no user-facing documentation changes (bug fix only; the collection-<name> /
route-<route> content key format is unchanged).

Summary of Changes

1. Split active content content keys on only the first hyphen so the value keeps any
   remaining hyphens, in packages/cli/src/plugins/resource/plugin-active-content.js
   (server /___graph.json handler) and packages/cli/src/data/client.js (client-side
   getContentByCollection / getContentByRoute when not prerendering).
2. Hyphenated collection names (e.g. my-posts) now resolve to their pages instead of [];
   hyphenated routes (e.g. /my-blog) keep their full value instead of being truncated to a
   prefix that over-matches.
3. Behavior for hyphen-free keys (graph, collection-nav, route-/blog) is unchanged.
4. Added regression test
   packages/cli/test/cases/develop.config.active-content-collection-hyphen/ that serves a
   collection named my-posts across two pages and asserts
   X-CONTENT-KEY: collection-my-posts returns those pages (fails with [] on unpatched source).
5. No breaking changes.