feat: add CLI access layer and release foundation

[tulayha]

Summary

• add a reusable application service boundary for CLI, Streamlit, workers, and future adapters
• replace the flat command surface with grouped Typer commands for indexing, search, actors, repositories, benchmarks, runtime checks, and UI launch
• add persistent named repository configuration with index and device selection
• provide consistent rich/JSON output, structured JSON errors, progress reporting, model preparation, and index lifecycle commands
• make vidxp ui the sole browser-interface entry point and remove legacy CLI aliases and vidxp-ui
• reconcile origin/main and the tagged v0.1.0 release history without regressing the new logo, README structure, or upstream wording
• publish automatic b prereleases from main to TestPyPI and approved stable releases manually from main to PyPI
• use Towncrier fragments for stable changelogs while Python Semantic Release remains the sole version authority

Why

VidXP needed one transport-neutral access boundary and a predictable,
automation-friendly CLI instead of duplicated frontend and command behavior.
Named repository configuration also makes local indexes centrally selectable
without coupling future API or MCP adapters to Typer.

The release history had also split between main and release. Bringing the
tagged stable ancestry back into the main line allows one branch to own
prereleases and stable releases without moving the existing tag.

Release and changelog behavior

• release and CI tools are declared once in utils/build-requirements.txt
• release-relevant merges to main create GitHub/TestPyPI b prereleases
• the protected Release (main → PyPI) workflow always checks out main
• stable releases render and consume pending fragments; prereleases retain them
• CI requires a fragment or a maintainer-applied skip-changelog label
• fragment enforcement stays inside the existing CI / validate check

User impact

The canonical command surface is grouped under vidxp index, vidxp search,
vidxp actors, vidxp repositories, and vidxp benchmark. Existing hidden
flat aliases and the standalone vidxp-ui executable are intentionally
removed; the supported UI command is vidxp ui.

Validation

• GitHub CI passes lint, 114 tests, and package build
• all workflows pass actionlint
• isolated Semantic Release runs calculated 0.2.0-b.1 and 0.2.0
• prerelease validation retained fragments and left CHANGELOG.md untouched
• stable validation rendered the Towncrier section and consumed the fragment
• both prerelease and stable validation built a wheel and source distribution
• README content was restored after PyPI link rewriting
• the v0.1.0 tag and origin/main are ancestors of the branch
• public-repository diff scan found no credentials, private keys, tokens, or local absolute paths