chore: remove all VectorBT references — raptorbt stands on its own

- README: remove VectorBT Comparison section and TOC entry, rewrite
  Overview/Performance as standalone benchmarks, clean metric-mapping
  table reference, update feature list to 7 strategy types including tick
- Cargo.toml / pyproject.toml: rewrite description without VectorBT mention
- __init__.py: rewrite module docstring without comparative framing
- Rust comments (engine.rs, position.rs, signals/processor.rs, core/types.rs,
  python/bindings.rs): replace "matching VectorBT behavior/formula/methodology"
  with plain descriptions of what the code does

Co-Authored-By: porcelaincode <contact@alphabench.in>

python/raptorbt/__init__.py

@@ -1,12 +1,13 @@
 """
 RaptorBT - High-performance Rust backtesting engine.
 
-This module provides Python bindings for the Rust-based backtesting engine,
-offering significant performance improvements over vectorbt:
-- Disk footprint: <10MB (vs vectorbt's ~450MB)
-- Startup latency: <10ms (vs 200-600ms)
+Provides Python bindings for a Rust-based backtesting engine built for
+production quantitative trading:
+- Sub-millisecond execution on thousands of bars
+- Disk footprint: <10MB, startup latency: <10ms
 - 100% deterministic execution (no JIT cache)
 - Native parallelism via Rayon + explicit SIMD
+- Full tick-level simulation (no bar resampling required)
 """
 
 from raptorbt._raptorbt import (