feat: v0.2.0 — Joplin import, ChatGPT Projects, --project filter

Core features:
- Add `joplin` command: syncs exported Markdown to Joplin via local REST API
- Notebooks auto-created per provider+project (e.g. "ChatGPT - My Project")
- Idempotent: notes updated (not duplicated) on re-run; note ID tracked in manifest
- Add `--project` filter to `export` and `list` commands (substring or 'none')
- Add ChatGPT Projects support via CHATGPT_PROJECT_IDS env var

Config:
- Add JOPLIN_API_TOKEN, JOPLIN_API_URL, JOPLIN_REQUEST_TIMEOUT
- Version now read from importlib.metadata (single source of truth: pyproject.toml)
- Bump version to 0.2.0

Quality:
- Explicit Timeout handling in JoplinClient with actionable error messages
- token validation (validate_token) separate from connectivity (ping)
- Remove debug_auth.py, debug_claude.py, and untracked .har file
- Add *.har to .gitignore (may contain auth cookies/session tokens)
- Update README, CHANGELOG, FUTURE.md to reflect v0.2.0

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -36,3 +36,6 @@ logs/
 *.swp
 *.swo
 Thumbs.db
+
+# HTTP traffic captures — may contain auth cookies and session tokens
+*.har