v0.7.0: fix #30 white box, watermark registry, FLUX/Samsung/ByteDance detection

First PyPI release since 0.6.11 (v0.6.12 was tagged but never published), so this bundles everything since.

Fixes

• White box on PNG removal (#30): removing a watermark from an RGBA PNG (the format the Gemini app exports) left a transparent rectangle that rendered as a solid white box on opaque viewers. The input alpha plane is now preserved, so the recovered pixels show through.
• Preserve upload format and quality when stripping metadata.
• identify now explains the unknown verdict inline (#22).

Visible watermark removal

• Unified known-watermark registry (#28): reverse-alpha only for the Gemini sparkle and the Doubao "豆包AI生成" strip. Exact native-resolution Doubao recovery from a captured alpha map, generalizing to any resolution via NCC alignment.
• erase gains an optional big-LaMa inpaint backend (--backend lama).

Detection (identify)

• New platforms: Samsung Galaxy, Black Forest Labs (FLUX), and ByteDance Volcano Engine C2PA.
• China TC260 AIGC label now detected in JPEG EXIF and in late or attribute-form PNG XMP, not only the namespaced element.
• TrustMark false-positive durability gate.

Pipeline and platform

• Intel XPU device support for the invisible pipeline (#24).
• Text detection runs at native resolution (capped), fixing small-text recall on large images (#27).

Infra

• Cross-platform CI matrix (ubuntu / macos / windows x py3.10 / 3.12) and PyPI classifiers (#25).