v0.29.2

• Gate each optional Format variant behind its Cargo feature: a build without toml has no Format::Toml at all, so naming a format the build never enabled is a compile error instead of a runtime refusal returned from deep inside load — and the eight paired refusal arms disappear with the variants they guarded
• Report the missing Cargo feature when opening a known format this build cannot read, instead of calling the file's format unknown: detect() answers only for available formats, and the new Format::unavailable names what is missing
• Offer exactly the --input-format values the running build can read, so a narrowed afdata binary never advertises a format it would then refuse