Add plugin category filters

[brsbl]

Summary

• replace Browse category sections with compact category filter pills and one card grid
• add the same full catalog category taxonomy to Installed plugins
• combine category filters with existing search, sorting, and pagination
• preserve plugin cards, installed rows, and their existing actions

Verification

• 14 focused plugin tests passed
• full-stack focused run: 48 tests passed
• Turbo typecheck passed for @bb/app and @bb/shared-ui
• branch dev app verified Browse All, Browse Host access, Installed All, and Installed Context & knowledge states

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