Add repository goals and source-grounded social plans - #39

What changed

• add repository goals for stars, forks, closed pull requests, and release downloads
• group goals by repository and show progress, deadlines, and suggested next steps
• turn each suggested action into publish-ready drafts for X, LinkedIn, and Mastodon
• add a fixed source library for each repository, managed from a dedicated Growth Studio modal
• reuse text, release notes, images, and videos from repository or website sources while allowing each post to select different assets
• preview attached source images and videos directly in generated proposals and reject fabricated media URLs
• add an intervention explicitly grounded in the latest verified releases, issues, and pull requests
• show the active AI provider and model in the intervention modal
• protect external source retrieval with protocol, redirect, private-address, timeout, and response-size checks
• ground social copy in the README, releases, issues, pull requests, source content, and verified repository metrics
• reject drafts that exceed platform limits or omit a required format
• support OpenAI, Anthropic, Gemini, OpenRouter, and OpenAI-compatible providers from the Preferences page
• persist goals, repository source libraries, and AI settings in SQLite
• show a layout-matched skeleton while goals are loading instead of leaving the page empty
• document the new settings and Docker environment variables

Checks

• npm test — 28 files, 151 tests passing
• npm run build — passing
• npm run typecheck — new code passes; the command still reports the existing optional-string errors in IssueList.tsx, PullRequestList.tsx, and TriageWorkspace.tsx, plus the existing CSS custom-property typing errors in tests/utils/colors.test.ts