[feature] Hashtag federation (in/out), hashtag client API endpoints (#2032)

* update go-fed

* do the things

* remove unused columns from tags

* update to latest lingo from main

* further tag shenanigans

* serve stub page at tag endpoint

* we did it lads

* tests, oh tests, ohhh tests, oh tests (doo doo doo doo)

* swagger docs

* document hashtag usage + federation

* instanceGet

* don't bother parsing tag href

* rename whereStartsWith -> whereStartsLike

* remove GetOrCreateTag

* dont cache status tag timelineability

internal/api/model/search.go

@@ -28,6 +28,7 @@ type SearchRequest struct {
 	Resolve           bool
 	Following         bool
 	ExcludeUnreviewed bool
+	APIv1             bool // Set to 'true' if using version 1 of the search API.
 }
 
 // SearchResult models a search result.
@@ -36,5 +37,6 @@ type SearchRequest struct {
 type SearchResult struct {
 	Accounts []*Account `json:"accounts"`
 	Statuses []*Status  `json:"statuses"`
-	Hashtags []*Tag     `json:"hashtags"`
+	// Slice of strings if api v1, slice of tags if api v2.
+	Hashtags []any `json:"hashtags"`
 }