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/strategy/ACTION_PLAN.md

@@ -365,8 +365,8 @@ Position Skill Seekers as **the universal documentation preprocessor** for the e
 2. **Implement Chunking for RAG** (8-12 hours)
    ```bash
    skill-seekers scrape --chunk-for-rag \
-       --chunk-size 512 \
-       --chunk-overlap 50 \
+       --chunk-tokens 512 \
+       --chunk-overlap-tokens 50 \
        --preserve-code-blocks
    ```
 

docs/strategy/KIMI_ANALYSIS_COMPARISON.md

@@ -139,8 +139,8 @@ skill-seekers scrape --format confluence     # Confluence storage format
 ```bash
 # New flag for embedding-optimized chunking
 skill-seekers scrape --chunk-for-rag \
-    --chunk-size 512 \
-    --chunk-overlap 50 \
+    --chunk-tokens 512 \
+    --chunk-overlap-tokens 50 \
     --add-metadata
 
 # Output: chunks with metadata for embedding