release: prepare version 0.5.2v0.5.2

Finalize the 0.5.2 changelog for lossless PDF pagination, session-scoped attachment continuation, deduplicated fetched files, and token-only cross-conversation resume.

Synchronize the project metadata, runtime package version, and uv lock entry at 0.5.2. Refresh the exceptiongroup typing-extensions marker emitted by the current uv resolver, and move changelog comparison links to the v0.5.2 release boundary.

Validated with uv lock --check, the complete 132-test suite, Ruff, mypy for 30 source files, source and wheel builds, packaged runtime assets, and application initialization from the installed wheel.

0 files changed, 0 insertions, 0 deletions