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>

.env.example

@@ -10,6 +10,13 @@
 # Token type: JWT (starts with "eyJ"). Typically valid for ~7 days.
 CHATGPT_SESSION_TOKEN=
 
+# ChatGPT Projects (optional): comma-separated list of project gizmo IDs.
+# Project conversations are NOT included in the default /conversations listing.
+# How to find: open chatgpt.com → click a Project → look at the browser URL:
+#   https://chatgpt.com/g/g-p-<ID>-<slug>/project  →  copy "g-p-<ID>"
+# Example: CHATGPT_PROJECT_IDS=g-p-68c2b2b3037c8191890036fb4ae3ed9f,g-p-anotherproject
+CHATGPT_PROJECT_IDS=
+
 # --- Claude ---
 # How to get: open claude.ai in Chrome → F12 → Application tab
 # → Cookies → https://claude.ai → find "sessionKey" → copy Value
@@ -26,6 +33,18 @@ EXPORT_DIR=./exports
 #   provider/year          → exports/claude/2024/file.md (ignores projects)
 OUTPUT_STRUCTURE=provider/project/year
 
+# --- Joplin ---
+# Automate importing exported conversations into Joplin as notes.
+# Requires Joplin desktop running with the Web Clipper service enabled.
+# How to get the token:
+#   Joplin → Tools → Options → Web Clipper → copy "Authorization token"
+JOPLIN_API_TOKEN=
+# API URL (default port is 41184; change only if you've customised it)
+JOPLIN_API_URL=http://localhost:41184
+# Request timeout in seconds (default: 30). Increase if Joplin times out on
+# large conversations. Example: JOPLIN_REQUEST_TIMEOUT=60
+# JOPLIN_REQUEST_TIMEOUT=30
+
 # --- Cache ---
 # Where the sync manifest and logs are stored (default: ~/.ai-chat-exporter)
 CACHE_DIR=~/.ai-chat-exporter