feat: add support for github enterprise instances

[jsngalloway]

This PR adds support for this plugin to communicate with self-hosted github instances. It does this by removing the hardcoded github.com and prompting the user fill in the full URL of the repo.

• tested this with a Github enterprise server
• tested with github.com for sanity
• tested migrating a github.com vault to the new settings - the update is transparent to the user, it assumes github.com since that was the only thing supported before

Here's what the config page looks like now:

• repository url - the full url of the repo e.g. https://github.com/jsngalloway/github-gitless-sync
• api base url - in the case that your github enterprise server vends its API on a differnet url, you can specify this here - otherwise it'll be inferred from the repository URL. I think the cases in which this are used will be very few and would consider removing if you think this is confusing.

There's some handy rejection logic:

Here's some logs that show it's interacting with a github enterprise server:

{"timestamp":"2026-08-30T22:01:43.050Z","level":"INFO","message":"Loading metadata"}
{"timestamp":"2026-08-30T22:01:43.054Z","level":"INFO","message":"Loaded metadata"}
{"timestamp":"2026-08-30T22:01:55.322Z","level":"INFO","message":"Starting first sync"}
{"timestamp":"2026-08-30T22:01:56.050Z","level":"ERROR","message":"Failed to get repo content","additional_data":{"status":409,"headers":{"access-control-allow-origin":"*","access-control-expose-headers":"ETag, Link, Location, Retry-After, X-GitHub-OTP, X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Used, X-RateLimit-Resource, X-RateLimit-Reset, X-OAuth-Scopes, X-Accepted-OAuth-Scopes, X-Poll-Interval, X-GitHub-Media-Type, X-GitHub-SSO, X-GitHub-Request-Id, Deprecation, Sunset","content-length":"162","content-security-policy":"default-src 'none'","content-type":"application/json; charset=utf-8","date":"Sun, 30 Aug 2026 22:01:55 GMT","github-authentication-token-expiration":"2026-09-29 17:31:19 -0400","referrer-policy":"origin-when-cross-origin, strict-origin-when-cross-origin","server":"GitHub.com","strict-transport-security":"max-age=31536000; includeSubdomains","x-accepted-github-permissions":"contents=read","x-content-type-options":"nosniff","x-github-api-version-selected":"2022-11-28","x-github-enterprise-version":"3.20.6","x-github-media-type":"github.v3; format=json","x-github-request-id":"8ba0f9d5-7f00-4f86-808c-771ced185175","x-ratelimit-limit":"150000","x-ratelimit-remaining":"149999","x-ratelimit-reset":"1788130915","x-ratelimit-resource":"core","x-ratelimit-used":"1","x-xss-protection":"0"},"arrayBuffer":{},"json":{"message":"Git Repository is empty.","documentation_url":"https://docs.github.com/enterprise-server@3.20/rest/git/trees#get-a-tree","status":"409"},"text":"{\n  \"message\": \"Git Repository is empty.\",\n  \"documentation_url\": \"https://docs.github.com/enterprise-server@3.20/rest/git/trees#get-a-tree\",\n  \"status\": \"409\"\n}\n"}}
{"timestamp":"2026-08-30T22:01:56.050Z","level":"INFO","message":"Remote repository is empty"}
{"timestamp":"2026-08-30T22:01:56.961Z","level":"INFO","message":"Starting first sync from local files"}
{"timestamp":"2026-08-30T22:01:58.134Z","level":"INFO","message":"Sync done"}

[jsngalloway]

removes hardcoded urls

[jsngalloway]

tests for sanity of URL parsing