The tag matching system (prefix matching, normalization, suggestions, tag_info metadata) currently only works for tags. When a user asks "How are posts by John Smith doing?" and the LLM sends any_author: "john smith", no resolution happens — the raw string goes straight to the API. If the casing or format doesn't match exactly, results may be empty.
The Mage API already supports find_keys for all meta types (ctx.mage["author"], ctx.mage["section"], ctx.mage["tag"]) with the same interface. We need to generalize the matching pipeline so authors and sections get the same treatment as tags.
Key differences: Authors/sections have no smart tag prefixes (parsely_smart:*) and no site-specific colon prefixes (tag:, ssts:). Their matching is simpler: search, normalize, exact match, suggestions.