fix: make tarball install fully self-contained (Python + kb_ai + port…

…ability checks) (#5)

* fix: use --no-editable for uv sync to embed kb_ai in site-packages

Without --no-editable, uv installs the local kb-ai package as an editable
reference via a .pth file pointing to the build machine's source directory
(e.g. /Users/runner/work/kaas/kaas/py/src). On the user's machine this path
doesn't exist, so `python3 -m kb_ai` fails with "No module named kb_ai".

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: add cross-machine portability checks to verify-install.sh

verify-install.sh previously passed on the build machine even when the
tarball contained broken absolute paths — because on the same machine those
paths resolve correctly. Add checks that catch cross-machine failures:

- Absolute symlinks under py/ pointing outside the install dir
- .pth files with absolute paths (editable installs)
- pyvenv.cfg home pointing to a foreign location
- kb_ai importability test

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: add CLAUDE.md

* docs: add local config setup instructions before make dev

Users need to create etc/kaas-dev.toml with LLM credentials before
running make dev. Added step-by-step instructions in both EN and CN READMEs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>