Remove skipped tests and unreachable RPC methods (bd-212, bd-213)

bd-212: Delete 3 permanently skipped test functions (~150 LOC)
- TestImportDependencyUpdates (import_collision_test.go)
- TestImportChainDependencies (import_collision_test.go)
- TestUpdateDependencyReferences (collision_test.go)

bd-213: Remove 4 unreachable RPC methods (~80 LOC)
- Server.GetLastImportTime
- Server.SetLastImportTime
- Server.findJSONLPath
- Client.Import

All tests pass. Phase 1 dead code cleanup continues.

internal/rpc/client.go

@@ -307,11 +307,6 @@ func (c *Client) Export(args *ExportArgs) (*Response, error) {
 	return c.Execute(OpExport, args)
 }
 
-// Import imports issues from JSONL format
-func (c *Client) Import(args *ImportArgs) (*Response, error) {
-	return c.Execute(OpImport, args)
-}
-
 // EpicStatus gets epic completion status via the daemon
 func (c *Client) EpicStatus(args *EpicStatusArgs) (*Response, error) {
 	return c.Execute(OpEpicStatus, args)