Add support for GITHUB_TOKEN environment variable

[arturo-skydio]

Add support for GITHUB_TOKEN environment variable in authentication
chain, providing compatibility with GitHub CLI and other GitHub tools.
Environment variable is checked after config file but before git
credential helper fallback.

Priority order:

1. Command line argument (--github-oauth)
2. Config file (~/.revupconfig)
3. Environment variable (GITHUB_TOKEN) [NEW]
4. Git credential helper
5. Error if none found

Features:

• Maintains all existing functionality and fallbacks
• Proper token redaction in logs for security
• Clear debug messaging showing which method was used
• Updated error message to mention environment variable option

This change improves user experience by allowing the same environment
variable used by gh and other GitHub tools, reducing setup friction.

Branch: main
Topic: env-token-support

[arturo-skydio]

Reviews in this chain:
└#216 Add support for GITHUB_TOKEN environment variable

[arturo-skydio]

#	head	base	diff	date	summary
0	2d97d1aa	9834d4c1	diff	Sep 4 15:42 PM	1 file changed, 16 insertions(+), 8 deletions(-)
1	4d86e7d8	9834d4c1	diff	Sep 4 18:31 PM	0 files changed
2	50d601a3	9834d4c1	diff	Sep 25 21:09 PM	1 file changed, 3 insertions(+), 3 deletions(-)
3	386fd727	9834d4c1	diff	Sep 30 23:48 PM	2 files changed, 10 insertions(+), 1 deletion(-)
4	b6ec92f0	9834d4c1	diff	Oct 1 2:38 AM	1 file changed, 9 deletions(-)

[jerry-skydio]

can we settle on supporting only GITHUB_TOKEN? I'd rather not have details from another project enter this codebase, and GITHUB_TOKEN seems more generic

[arturo-skydio]

can we settle on supporting only GITHUB_TOKEN? I'd rather not have details from another project enter this codebase, and GITHUB_TOKEN seems more generic

Yup, I'll just change it to accept GITHUB_TOKEN

[jerry-skydio]

nit: spelling

[jerry-skydio]

don't add this file in this PR. make a dedicated pr if you need this

[arturo-skydio]

oh yea, didn't actually mean to commit this file, removed now