feat(lexicon): sync current AT Protocol video definitions

[ewanc26]

Summary

• sync the bundled lexicon snapshot to the current official bluesky-social/atproto corpus (402 documents, 319 query/procedure definitions)
• add current multipart video schemas and refresh changed actor/feed/video definitions
• add a binary XRPC upload API with percent-encoded query parameters for app.bsky.video.uploadPart
• prevent the C++ generator from emitting invalid body-less wrappers for binary-input procedures
• align README/module/video metadata with the generated C API

Stability and resource impact

• keeps binary bodies as caller-owned byte views; no extra full-payload copy is introduced
• the lexicon generator remains a development-time C++ tool and generated runtime code remains C23
• pins endpoint, binary-procedure, and output-decoder counts in the generator tests

Verification

• full local build completed
• ctest --test-dir build --output-on-failure -j2: 125/125 passed
• generated header compiles as C11/C23-compatible C