refactor: rename all chunk flags to include explicit units

Replace ambiguous --chunk-size / --chunk-overlap names that meant different
things in different contexts (tokens vs characters) with fully explicit names:

- --chunk-size (RAG tokens)     → --chunk-tokens
- --chunk-overlap (RAG tokens)  → --chunk-overlap-tokens
- --chunk (enable RAG chunking) → --chunk-for-rag
- --streaming-chunk-size (chars) → --streaming-chunk-chars
- --streaming-overlap (chars)    → --streaming-overlap-chars
- --chunk-size (PDF pages)       → --pdf-pages-per-chunk (poc file)

Also aligns stream_parser.py help with streaming_ingest.py standalone parser.
All 2167 tests pass.

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

src/skill_seekers/cli/rag_chunker.py

@@ -383,8 +383,8 @@ def main():
     )
     parser.add_argument("skill_dir", type=Path, help="Path to skill directory")
     parser.add_argument("--output", "-o", type=Path, help="Output JSON file")
-    parser.add_argument("--chunk-size", type=int, default=512, help="Target chunk size in tokens")
-    parser.add_argument("--chunk-overlap", type=int, default=50, help="Overlap size in tokens")
+    parser.add_argument("--chunk-tokens", type=int, default=512, help="Target chunk size in tokens")
+    parser.add_argument("--chunk-overlap-tokens", type=int, default=50, help="Overlap size in tokens")
     parser.add_argument("--no-code-blocks", action="store_true", help="Don't preserve code blocks")
     parser.add_argument("--no-paragraphs", action="store_true", help="Don't preserve paragraphs")
 
@@ -392,8 +392,8 @@ def main():
 
     # Create chunker
     chunker = RAGChunker(
-        chunk_size=args.chunk_size,
-        chunk_overlap=args.chunk_overlap,
+        chunk_size=args.chunk_tokens,
+        chunk_overlap=args.chunk_overlap_tokens,
         preserve_code_blocks=not args.no_code_blocks,
         preserve_paragraphs=not args.no_paragraphs,
     )