fix: resolve all R CMD check errors and notes

- Wrap get_fips/get_stabbr examples in dontrun (tidycensus is Suggests)
- Add .gitea to .Rbuildignore (hidden dir note)
- Add importFrom(datasets, state.abb/state.name) for postcode_lookup
- Remove LazyData: true (no data/ directory)

man/get_fips.Rd

@@ -16,7 +16,8 @@ FIPS codes that match the abbreviation
 Get the FIPS code for a given state abbreviation
 }
 \examples{
+\dontrun{
 get_fips("MT")
 get_fips("PR")
-get_fips("CC")
+}
 }

man/get_stabbr.Rd

@@ -16,5 +16,7 @@ a character value, length 2, with the state abbreviation
 Get the state abbreviation from a given FIPS Code
 }
 \examples{
+\dontrun{
 get_stabbr("06")
 }
+}