DDOC-1134: Add common error codes

[kojimaru14]

Description

Updates the Common error codes guide to document additional 400 OAuth/JWT-style errors (and related cleanup), adds invalid_token under 401 Unauthorized

Fixes # (issue)
Re DDOC-1134

Changes

• Add rows for common token and JWT assertion errors (unauthorized_client, invalid_client, invalid_grant / invalid_request variants, etc.) and reorder the exp-claim invalid_grant row next to related entries.
• Remove the redundant generic invalid_grant authorization-code message that duplicated newer rows.
• Document invalid_token (401) with guidance on invalid/expired tokens and link to Refresh a token via guide://authentication/tokens/refresh.

Checklist

• [ y ] My code follows the style guidelines of this project
• [ y ] I have performed a self-review of my own changes
• [ n ] I have run yarn lint to make sure my changes pass all linters
• [ y ] I have pulled the latest changes from the upstream developer branch

[kojimaru14]

@ianfre25 Thank you for approving the change!

I see that CI for yarn lint failed due to the following error

[2] $ mdspell 'content/**/*.md' '!content/guides/box-ai/ai-agents/*.md' README.md CONTRIBUTING.md -a -n --en-us -d content/dictionaries/en_US -r
[2]     content/guides/api-calls/permissions-and-errors/common-errors.md
[2]        74 | type is unauthorized for this client_id. | 
[2]        75 | type is unauthorized for this client_id](https://support.box.com/hc/e 

https://github.com/box/developer.box.com/actions/runs/24797619426/job/72842248544

It appears that mdspell doesn't like "client_id" and treats it as misspelled. I have added "client_id" to content/dictionaries/en_US.dic since this is the word used in the raw error message and shouldn't be treated like that.