chore: bump version to 3.3.0 and finalize changelog

- Bump version in pyproject.toml: 3.2.0 -> 3.3.0
- Rename [Unreleased] to [3.3.0] - 2026-03-16 with theme line
- Add Supported Source Types (17) reference table
- Add 12 missing changelog entries:
  - feat: sync-config command (#306)
  - feat: best practices guide (#206)
  - docs: 32 files updated for 17 source types
  - docs: README translations for 10 languages
  - perf: pre-compiled regex, bisect line indexing, O(1) dedup (#309)
  - fix: Invalid IPv6 URL on bracket URLs (#284)
  - fix: GitHub scraper PaginatedList crash (#269)
  - fix: release workflow version mismatch and 3.10 compat
  - fix: infer_categories key mismatch
  - fix: flaky benchmark test
  - fix: CI branch protection pending

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "skill-seekers"
-version = "3.2.0"
+version = "3.3.0"
 description = "Convert documentation websites, GitHub repositories, and PDFs into Claude AI skills. International support with Chinese (简体中文) documentation."
 readme = "README.md"
 requires-python = ">=3.10"