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/streaming_ingest.py

@@ -380,9 +380,9 @@ def main():
 
     parser = argparse.ArgumentParser(description="Stream and chunk skill documents")
     parser.add_argument("input", help="Input file or directory path")
-    parser.add_argument("--chunk-size", type=int, default=4000, help="Chunk size in characters")
+    parser.add_argument("--streaming-chunk-chars", type=int, default=4000, help="Chunk size in characters")
     parser.add_argument(
-        "--chunk-overlap", type=int, default=200, help="Chunk overlap in characters"
+        "--streaming-overlap-chars", type=int, default=200, help="Chunk overlap in characters"
     )
     parser.add_argument("--batch-size", type=int, default=100, help="Batch size for processing")
     parser.add_argument("--checkpoint", help="Checkpoint file path")
@@ -390,7 +390,7 @@ def main():
 
     # Initialize ingester
     ingester = StreamingIngester(
-        chunk_size=args.chunk_size, chunk_overlap=args.chunk_overlap, batch_size=args.batch_size
+        chunk_size=args.streaming_chunk_chars, chunk_overlap=args.streaming_overlap_chars, batch_size=args.batch_size
     )
 
     # Progress callback