Add missing test coverage and harden open package

[arbourd]

• Add TestGetURLErrors (not-a-git-repo, local remote, unsupported provider)
• Add TestGetURLBareRepo covering the AbsoluteGitDir bare-repo fallback
• Add TestConfigGetRegexp and TestLoadProvidersLocal for new gitw behaviour
• Rename url → openURL in GetURL to fix net/url import shadowing
• Add -- before URL in open/xdg-open to prevent flag injection
• LoadProviders reads local git config before falling back to global
• Move git config I/O into gitw.ConfigGetRegexp; open package no longer
  imports go-git-cmd-wrapper directly

[Copilot]

Pull request overview

Adds missing test coverage for error paths and bare-repo handling in the open package, hardens the browser-launch commands against flag injection by inserting -- before the URL, eliminates a net/url import shadowing by renaming a local variable, and centralizes the git config --get-regexp invocation in the gitw package so that LoadProviders now picks up local repo configuration in addition to global.

Changes:

• New tests: TestGetURLErrors, TestGetURLBareRepo, TestLoadProvidersLocal, TestConfigGetRegexp.
• open: insert -- separator in open/xdg-open invocations and rename shadowing url variable to openURL.
• gitw: new ConfigGetRegexp wrapper consumed by open.LoadProviders, dropping open's direct dependency on go-git-cmd-wrapper.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
open/provider.go	Replaces direct git config call with gitw.ConfigGetRegexp; drops dependency on go-git-cmd-wrapper.
open/provider_test.go	Adds TestLoadProvidersLocal covering local-config provider discovery.
open/open.go	Adds -- separator to open/xdg-open and renames url to openURL to fix shadowing.
open/open_test.go	Adds error-path and bare-repo coverage for GetURL.
gitw/gitw.go	Adds ConfigGetRegexp wrapper; imports config subpackage.
gitw/gitw_test.go	Adds TestConfigGetRegexp exercising local config retrieval.
AGENTS.md	Updates docs to reflect new wrapper, tests, and local-config precedence.

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