Add ANN search support for vec0 virtual table

Add approximate nearest neighbor infrastructure to vec0: shared distance
dispatch (vec0_distance_full), flat index type with parser, NEON-optimized
cosine/Hamming for float32/int8, amalgamation script, and benchmark suite
(benchmarks-ann/) with ground-truth generation and profiling tools. Remove
unused vec_npy_each/vec_static_blobs code, fix missing stdint.h include.

scripts/amalgamate.py

@@ -0,0 +1,119 @@
+#!/usr/bin/env python3
+"""
+Amalgamate sqlite-vec into a single distributable .c file.
+
+Reads the dev sqlite-vec.c and inlines any #include "sqlite-vec-*.c" files,
+stripping LSP-support blocks and per-file include guards.
+
+Usage:
+    python3 scripts/amalgamate.py sqlite-vec.c > dist/sqlite-vec.c
+"""
+
+import re
+import sys
+import os
+
+
+def strip_lsp_block(content):
+    """Remove the LSP-support pattern:
+        #ifndef SQLITE_VEC_H
+        #include "sqlite-vec.c" // ...
+        #endif
+    """
+    pattern = re.compile(
+        r'^\s*#ifndef\s+SQLITE_VEC_H\s*\n'
+        r'\s*#include\s+"sqlite-vec\.c"[^\n]*\n'
+        r'\s*#endif[^\n]*\n',
+        re.MULTILINE,
+    )
+    return pattern.sub('', content)
+
+
+def strip_include_guard(content, guard_macro):
+    """Remove the include guard pair:
+        #ifndef GUARD_MACRO
+        #define GUARD_MACRO
+        ...content...
+        (trailing #endif removed)
+    """
+    # Strip the #ifndef / #define pair at the top
+    header_pattern = re.compile(
+        r'^\s*#ifndef\s+' + re.escape(guard_macro) + r'\s*\n'
+        r'\s*#define\s+' + re.escape(guard_macro) + r'\s*\n',
+        re.MULTILINE,
+    )
+    content = header_pattern.sub('', content, count=1)
+
+    # Strip the trailing #endif (last one in file that closes the guard)
+    # Find the last #endif and remove it
+    lines = content.rstrip('\n').split('\n')
+    for i in range(len(lines) - 1, -1, -1):
+        if re.match(r'^\s*#endif', lines[i]):
+            lines.pop(i)
+            break
+
+    return '\n'.join(lines) + '\n'
+
+
+def detect_include_guard(content):
+    """Detect an include guard macro like SQLITE_VEC_IVF_C."""
+    m = re.match(
+        r'\s*(?:/\*[\s\S]*?\*/\s*)?'  # optional block comment
+        r'#ifndef\s+(SQLITE_VEC_\w+_C)\s*\n'
+        r'#define\s+\1',
+        content,
+    )
+    return m.group(1) if m else None
+
+
+def inline_include(match, base_dir):
+    """Replace an #include "sqlite-vec-*.c" with the file's contents."""
+    filename = match.group(1)
+    filepath = os.path.join(base_dir, filename)
+
+    if not os.path.exists(filepath):
+        print(f"Warning: {filepath} not found, leaving #include in place", file=sys.stderr)
+        return match.group(0)
+
+    with open(filepath, 'r') as f:
+        content = f.read()
+
+    # Strip LSP-support block
+    content = strip_lsp_block(content)
+
+    # Strip include guard if present
+    guard = detect_include_guard(content)
+    if guard:
+        content = strip_include_guard(content, guard)
+
+    separator = '/' * 78
+    header = f'\n{separator}\n// Begin inlined: {filename}\n{separator}\n\n'
+    footer = f'\n{separator}\n// End inlined: {filename}\n{separator}\n'
+
+    return header + content.strip('\n') + footer
+
+
+def amalgamate(input_path):
+    base_dir = os.path.dirname(os.path.abspath(input_path))
+
+    with open(input_path, 'r') as f:
+        content = f.read()
+
+    # Replace #include "sqlite-vec-*.c" with inlined contents
+    include_pattern = re.compile(r'^#include\s+"(sqlite-vec-[^"]+\.c)"\s*$', re.MULTILINE)
+    content = include_pattern.sub(lambda m: inline_include(m, base_dir), content)
+
+    return content
+
+
+def main():
+    if len(sys.argv) != 2:
+        print(f"Usage: {sys.argv[0]} <input-file>", file=sys.stderr)
+        sys.exit(1)
+
+    result = amalgamate(sys.argv[1])
+    sys.stdout.write(result)
+
+
+if __name__ == '__main__':
+    main()