v2.33.7 — read/write symmetry audit + get_frame_range

Read/write symmetry audit and a gap it surfaced.

• Added scripts/audit_readwrite_symmetry.py + generated docs/reference/readwrite-symmetry.md — scans every tool's action surface and reports set_/add_/create_ writes lacking a read counterpart, so write-without-read gaps surface before users hit them. A repeatable feature-discovery method.
• Added fusion_comp(action="get_frame_range") — reads the comp's render frame range, the read counterpart to set_frame_range (a gap the audit found).

Live-validated on DaVinci Resolve Studio 21.0.0.