docs: mark one-click package as legacy v1.2.6 build

chore: bump project version to 1.2.7

docs: simplify README layout and remove upload-post doc

docs: streamline README structure and remove roadmap

docs: clarify recommended setup and entry points

build: adopt uv-based environment and dependency management

fix: harden file path access in video endpoints

fix: recover malformed local image metadata

fix: stabilize final audio export settings

fix: guard empty random bgm selection

fix: avoid repeated re-encoding when merging video clips

docs: clarify openai-compatible provider configuration

fix: sort local video materials deterministically

fix: prevent subtitle clipping in multiline captions

fix: validate chat completion response content