Overhaul build system scripts tools

Consolidate build configuration logic into scripts tool
Extract common utilities:
- Move platform-independent build setup from SConstruct to tools/scripts.py
- Extract string utilities (to_raw_cstring, to_escaped_cstring) to build/string.py
- Add common_compiler_flags.py for shared compiler configuration
- Simplify SConstruct
- Update build modules to use extracted string utilities instead of env methods
- Refactor cache.py progress tracking to use atexit callbacks
- Parameterize git info functions to support custom prefixes
- Remove tools/targets.py and tools/macos_osxcross.py (functionality consolidated)
- Update .gitignore for SCons output files
- Disable use_static_cpp for hot_release on linux platform

Author: Spartan322

.gitignore

@@ -163,4 +163,6 @@ cython_debug/
 
 # When configure fails, SCons outputs these
 config.log
-.sconf_temp
+.sconsign*.dblite
+.scons_env.json
+.scons_node_count