dts: declaration maps (.d.ts.map) are not updated after Ivy members are injected #693

Found while reviewing #683.

The dts plugin rewrites .d.ts text in generateBundle (adds import * as i0 … and the static ɵ… members) but leaves the declaration map alone. In rolldown, the written .d.mts.map is a separate asset that is already in the bundle at that point, so it keeps the old line numbers.

tsdown / rolldown-plugin-dts with dts sourcemap: .d.mts.map is byte-identical with and without the members
line 1 is now `import * as i0 …`, so the first mapping (meant for HelloComponent) points at the import,
and every later class is off by 1 + (number of added member lines)
→ go-to-definition in a consumer's IDE opens the wrong line of the source .ts

The asset path has the same gap. A fix needs the injection points: injectDtsDeclarations only returns the new string, and it doesn't always add whole lines (it splits declare class X {} before the }). Options: have dts_inject return its splices and shift the map (mappings groups per line), or inject from a renderChunk (order: 'post') hook that returns a map. Reviewers checked that rolldown chains such a map, and it also keeps the [hash] of hashed .d.ts chunks in sync.