[bugfix] process account delete synchronously to prevent OOM (#4260)

# Description

- updates account delete processing to handle side-effects synchronously to prevent OOM
- updates account delete processing to check more often if account.IsLocal() for certain deletes / side-effects
- ensures that mutes get removed from database on delete

## Checklist

- [x] I/we have read the [GoToSocial contribution guidelines](https://codeberg.org/superseriousbusiness/gotosocial/src/branch/main/CONTRIBUTING.md).
- [x] I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
- [x] I/we have not leveraged AI to create the proposed changes.
- [x] I/we have performed a self-review of added code.
- [x] I/we have written code that is legible and maintainable by others.
- [x] I/we have commented the added code, particularly in hard-to-understand areas.
- [ ] I/we have made any necessary changes to documentation.
- [ ] I/we have added tests that cover new code.
- [ ] I/we have run tests and they pass locally with the changes.
- [x] I/we have run `go fmt ./...` and `golangci-lint run`.

Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4260
Co-authored-by: kim <grufwub@gmail.com>
Co-committed-by: kim <grufwub@gmail.com>

internal/util/fns.go

@@ -32,18 +32,7 @@ func Must(fn func()) {
 		panic("nil func")
 	}
 	for !func() (done bool) {
-		defer func() {
-			if r := recover(); r != nil {
-				// Gather calling func frames.
-				pcs := make([]uintptr, 10)
-				n := runtime.Callers(3, pcs)
-				i := runtime.CallersFrames(pcs[:n])
-				c := gatherFrames(i, n)
-
-				const msg = "recovered panic: %v\n\n%s\n"
-				fmt.Fprintf(os.Stderr, msg, r, c.String())
-			}
-		}()
+		defer Recover()
 		fn()
 		done = true
 		return
@@ -51,6 +40,21 @@ func Must(fn func()) {
 	}
 }
 
+// Recover wraps runtime.recover() to dump the current
+// stack to stderr on panic and return the panic value.
+func Recover() any {
+	if r := recover(); r != nil {
+		// Gather calling func frames.
+		pcs := make([]uintptr, 10)
+		n := runtime.Callers(3, pcs)
+		i := runtime.CallersFrames(pcs[:n])
+		c := gatherFrames(i, n)
+		fmt.Fprintf(os.Stderr, "recovered panic: %v\n\n%s\n", r, c.String())
+		return r
+	}
+	return nil
+}
+
 // gatherFrames collates runtime frames from a frame iterator.
 func gatherFrames(iter *runtime.Frames, n int) errors.Callers {
 	if iter == nil {