feat: add Ideas browser admin page (v0.5.1)

New submenu page showing all article ideas from the content analyzer.
Displays title, type, relevance score, frequency, key points, and
keywords with type filtering and pagination. Gives live visibility
into the idea pipeline.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -5,6 +5,15 @@ All notable changes to PRAutoBlogger will be documented in this file.
 Format follows [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project uses [Semantic Versioning](https://semver.org/).
 
+## [0.5.1] — 2026-04-20
+
+### Added
+- **Ideas browser admin page.** New "Ideas" submenu under PRAutoBlogger showing
+  all article ideas collected by the content analyzer. Displays suggested title,
+  topic, type (question/complaint/comparison/news/guide), relevance score bar,
+  frequency, key points, and target keywords. Filterable by type with count
+  badges. Paginated at 30 per page, newest first.
+
 ## [0.5.0] — 2026-04-20
 
 ### Added