feat: integrate Google Scholar alerts and improve paper filtering pipeline

- Add Google Scholar Alert collection via Gmail IMAP
- Add Gmail App Password based authentication
- Add Google Scholar environment variables to NAS compose configuration
- Enable Google Scholar Alert source in config.nas.yaml
- Disable subject filtering that incorrectly excluded Scholar alert emails
- Parse paper titles and links from Google Scholar alert HTML emails
- Deduplicate collected Scholar papers by normalized title
- Filter Scholar UI/control links such as update alert and unsubscribe entries
- Filter bracket-only alert labels such as [automotive radar]

- Add Google Scholar specific relevance threshold
- Keep global min_relevance at 2
- Set Google Scholar minimum relevance to 3
- Reduce Scholar candidates from 229 collected / 207 merged to 28 accepted

- Add Gemini API rate limiting
- Enforce minimum 13 second interval between Gemini requests
- Apply shared rate limiter to abstract and full-text enrichment
- Prevent Gemini free-tier 5 RPM quota errors
- Verify retry processing of previously failed AI enrichment jobs

- Verify end-to-end NAS workflow
- Google Scholar Alert collection successful
- Gemini enrichment successful without HTTP 429 errors
- Joplin report generation and WebDAV synchronization successful

docker-compose.nas.yml

@@ -18,8 +18,8 @@ services:
       OPENAI_API_KEY: ${OPENAI_API_KEY:-}
       GEMINI_API_KEY: ${GEMINI_API_KEY}
       GROQ_API_KEY: ${GROQ_API_KEY}
-      GMAIL_ADDRESS: ${GMAIL_ADDRESS:-}
-      GMAIL_APP_PASSWORD: ${GMAIL_APP_PASSWORD:-}
+      GOOGLE_SCHOLAR_GMAIL_ADDRESS: ${GOOGLE_SCHOLAR_GMAIL_ADDRESS}
+      GOOGLE_SCHOLAR_GMAIL_APP_PASSWORD: ${GOOGLE_SCHOLAR_GMAIL_APP_PASSWORD}
 
       # Existing Joplin WebDAV sync target
       JOPLIN_WEBDAV_URL: ${JOPLIN_WEBDAV_URL}