Updates species dictionary path for RMG

[calvinp0]

Updates the species dictionary path to "dictionary.txt" to align with the expected file name for RMG kinetics libraries, whereas thermo uses "species_dictionary.txt".

It appears that RMG, since 3.9, prefers it to be called dictionary.txt

[Copilot]

Pull request overview

This PR updates the species dictionary filename from "species_dictionary.txt" to "dictionary.txt" in the save_thermo_lib function to align with RMG 3.9+ conventions.

Changes:

• Modified arc/plotter.py to change the species dictionary filename for thermo libraries from "species_dictionary.txt" to "dictionary.txt"
• Added a comment explaining the naming convention difference between kinetics and thermo libraries

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[Copilot]

There is a critical discrepancy between the PR description and the code changes. The PR description states "Updates the species dictionary path to 'dictionary.txt' to align with the expected file name for RMG kinetics libraries, whereas thermo uses 'species_dictionary.txt'." This clearly states that kinetics libraries expect dictionary.txt and thermo uses species_dictionary.txt. However, this change is being made in the save_thermo_lib function (line 770 docstring confirms it "Save an RMG thermo library"), not the save_kinetics_lib function. The code change contradicts the PR description. Either the PR description is incorrect, or the change is being applied to the wrong function. Based on the documentation in docs/source/output.rst which shows kinetics libraries having dictionary.txt, it appears that save_kinetics_lib (line 909) should be updated instead of or in addition to this function.