Release 3.0.2: fix collection, API, UI and Docker workflows

[DavidVoitenko]

Changes

• Make source retries atomic and enforce source, line, and per-target request limits.
• Fix API validation, idempotent mutations, scoped pagination, and SSE lifecycle.
• Repair API-key permissions, import mapping, stale previews, and tab visibility.
• Make Docker's gateway and service presets usable; update setup examples and repository metadata.
• Bump the application and package to 3.0.2.

Verification

• Full local suite: 3,718 tests, no failures (2 expected platform/schema skips).
• Wheel verification and installed-product smoke passed.
• All eight UI tabs rendered at desktop and mobile widths in headless Chromium without JavaScript errors or page overflow.
• A temporary live quick-source collection returned 7,838 unique candidates.
• GitHub CI is running across Linux, macOS, and Windows.