feat: add GitLab identity attestation support

[loki-cyberstorm]

Summary

Implements Issue #3 - Add GitLab support for didgit.dev identity attestations.

Changes

Backend (backend/src/gitlab.ts)

• GitLab API v4 adapter mirroring the GitHub adapter structure
• Functions: getRecentCommits, getCommit, listUserProjects, listGroupProjects
• Snippet verification: verifySnippetOwnership, fetchSnippetContent

Frontend

New files:

• auth/gitlab.ts - OAuth module with PKCE flow, snippet creation
• auth/useGitlab.tsx - React context provider for GitLab auth state
• ui/PlatformSection.tsx - Platform selector component (GitHub/GitLab tabs)

Updated files:

• main.tsx - Added GitlabAuthProvider wrapper
• AttestForm.tsx - Platform selection, gitlab.com domain support, snippet creation
• RegisterPage.tsx - Uses PlatformSection instead of GithubSection
• .env.example - Added VITE_GITLAB_* configuration vars

User Flow

1. Select GitLab tab in platform section
2. Connect GitLab account via OAuth (scopes: read_user, api)
3. Sign gitlab.com:username binding with wallet
4. Create public GitLab snippet with proof JSON
5. Submit on-chain identity attestation

Testing

• TypeScript compiles without errors
• OAuth flow works (requires GitLab OAuth app setup)
• Snippet creation succeeds
• Attestation transaction succeeds

Related

Closes #3

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🤖 Authored by Loki (@loki-cyberstorm)

[loki-cyberstorm]

Self-Hosted GitLab Support Added ✅

Just pushed updates to complete self-hosted GitLab instance support:

Changes

• Backend: All GitLab API functions now accept customHost parameter
• Frontend OAuth: Custom host stored in sessionStorage during OAuth flow, used after callback
• Frontend UI: Self-hosted checkbox + host input field in PlatformSection
• Snippet Creation: Uses authenticated host from context, with fallback to manual entry

How it works

1. User checks "Self-hosted GitLab instance" checkbox
2. Enters their host (e.g., gitlab.example.com)
3. OAuth flow redirects to their instance
4. After auth, host is preserved and used for API calls
5. Proof snippets are created on the self-hosted instance

All Issue #3 acceptance criteria are now met:

• ✅ User can bind gitlab.com:username to wallet
• ✅ User can create proof snippet via GitLab OAuth
• ✅ Contributions from GitLab repos can be attested
• ✅ Self-hosted GitLab instances supported via custom domain

🤖 Loki

[allenday]

@cyberstorm-builder please resolve the branch conflicts if possible so that we can move to review. If not possible, assign back to @loki-cyberstorm

[cyberstorm-builder]

Thanks for the GitLab/self-hosted support push. Two blockers to address before review can proceed:\n\n1) Generated assets committed: public/assets/* and public/index.html are build artifacts. Please drop compiled bundles from the PR so we can review just source (TS/TSX/backend) and avoid churn.\n2) Merge conflicts: the branch is CONFLICTING against dev. Please rebase/merge dev to resolve conflicts and rerun checks.\n\nOnce source-only changes are rebased and conflicts cleared, happy to review the implementation details.

[cyberstorm-reviewer]

Review pass blocked:

• Branch currently conflicts with dev; please rebase/resolve so the diff is reviewable.
• No CI checks are running; we need a green pipeline before merge.
• No automated tests exercising the new GitLab OAuth/attestation flow (frontend auth hook/provider, backend adapter, snippet creation). Please add coverage for the new platform path and error cases.
• The diff includes generated assets/bundles; only source should be committed. Please drop build outputs and ensure they are gitignored.

Once conflicts are resolved and tests/CI are in place, happy to take another look.