Problem: `pending.Metadata` used shorthand field names (`cat`, `rec`,
`rec_mode`) matching user-facing token syntax, coupling internal
representation to config. `RecurSpec.from_completion` used a boolean
where a `pending.RecurMode` alias exists. `category_syntax` was
hardcoded to `'cat'` with no config option.
Solution: rename `Metadata` fields to `category`/`recur`/`recur_mode`,
add `category_syntax` config option (default `'cat'`), rename
`ParsedEntry` fields to match, replace `RecurSpec.from_completion`
with `mode: pending.RecurMode`, and restore `[string]` indexer on
`pending.ForgeConfig` alongside explicit fields.
Barrett Ruth
05871fa1a5