docs: update all chunk flag names to match renamed CLI flags

Replace all occurrences of old ambiguous flag names with the new explicit ones:
  --chunk-size (tokens)  → --chunk-tokens
  --chunk-overlap        → --chunk-overlap-tokens
  --chunk                → --chunk-for-rag
  --streaming-chunk-size → --streaming-chunk-chars
  --streaming-overlap    → --streaming-overlap-chars
  --chunk-size (pages)   → --pdf-pages-per-chunk

Updated: CLI_REFERENCE (EN+ZH), user-guide (EN+ZH), integrations (Haystack,
Chroma, Weaviate, FAISS, Qdrant), features/PDF_CHUNKING, examples/haystack-pipeline,
strategy docs, archive docs, and CHANGELOG.

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

docs/integrations/CHROMA.md

@@ -223,7 +223,7 @@ skill-seekers package output/codebase --target langchain
 
 **Option D: RAG-Optimized Chunking**
 ```bash
-skill-seekers scrape --config configs/fastapi.json --chunk-for-rag --chunk-size 512
+skill-seekers scrape --config configs/fastapi.json --chunk-for-rag --chunk-tokens 512
 skill-seekers package output/fastapi --target langchain
 ```
 
@@ -968,7 +968,7 @@ collection.add(
 
 2. **Implement Semantic Chunking:**
    ```bash
-   skill-seekers scrape --config configs/fastapi.json --chunk-for-rag --chunk-size 512
+   skill-seekers scrape --config configs/fastapi.json --chunk-for-rag --chunk-tokens 512
    ```
 
 3. **Set Up Multi-Collection Search:**