Extract and type the GitHub client module

[itsmiso-ai]

Parent umbrella issue: #616
Source audit: Weekly tech debt audit: dispatch - 2026-07-15
Source audit date: 2026-07-15

Recommendation

Problem: src/lib/github.ts is 1049 lines spanning JWT auth, issue CRUD, PR queries, CI log fetching, code search, and repo metadata. One helper (fetchRepoJson) returns Promise<any>. Module bloat makes it hard to reason about, test in isolation, and change without risk.

Evidence:

• src/lib/github.ts — 1049 lines
• Line 529: async function fetchRepoJson(repoFullName: string, errorPrefix: string): Promise<any>
• Mixed responsibilities: auth setup (lines 14–100), issue fetch (lines 150–250), PR logic (lines 260–520), log fetching (lines 808–878), code search (lines 1006–1049)

Acceptance: Split into github-auth.ts, github-issues.ts, github-ci.ts, github-code-search.ts (or equivalent domain files). fetchRepoJson typed with Record<string, unknown> instead of any. Each new file under 400 lines.