Implements the 7th audit script referenced in python.md §17.8. Scans
src/*.py for local imports (§17.9a), _PREFIX aliasing (§17.9b), and
repeated .from_dict() in the same expression (§17.9c, info-only).
Three changes in this commit:
1. scripts/audit_imports.py: AST-based scanner; exits 1 in --strict on
LOCAL_IMPORT or PREFIX_ALIAS. Whitelist-aware via
scripts/audit_imports_whitelist.toml (load with --show-whitelist;
disable with --no-whitelist).
2. scripts/audit_imports_whitelist.toml: 21 files whitelisted with per-file
reason (vendor SDK warmup, hot-reload re-imports, circular-dep avoidance).
Suppresses 187 LOCAL_IMPORT sites; 0 strict violations remain.
3. conductor/code_styleguides/python.md: updated §17.8 (4th audit entry)
and §17.9a (3 documented exceptions + whitelist mechanism).
Tests: tests/test_audit_imports.py (7 tests, all passing).
