appview: integrate label-value search and DID resolution in handlers
Use shared searchquery helpers (ResolveAuthor, ExtractTextFilters) to
replace duplicated resolution logic in both issue and pull handlers.
Wire up dynamic tag extraction for label-value queries. When label
definitions with DID format are present, resolve handle values to DIDs
at query time via ResolveDIDLabelValues.
Signed-off-by: Thomas Karpiniec <tom.karpiniec@outlook.com>