Harden credential privacy and packaging

[lukisch]

Changes

• Store saved Ollama credentials through the OS credential backend with explicit, conflict-safe migration; avoid plaintext fallback and unauthenticated retries, and sanitize provider errors.
• Make workspace export reviewable before writing, limit excerpts to selected completed documents, and clarify that exports are not anonymized. Keep PWA workspace data session-only and correct its offline guidance.
• Separate the environment bootstrap from the setuptools entry point; build a real src* runtime package and include selected license files.
• Replace unsupported privacy, security, SLA, SBOM, compatibility, and legal guarantees with scoped data-flow and inventory descriptions. Preserve version 1.0.0.

Validation

• Python 3.13.15 local Venv: pytest -q — 200 passed, 0 skipped, 5 existing Qt deprecation warnings. The Venv inherits system site-packages, so this is not described as hermetic.
• The packaging contract builds wheel and sdist, installs the wheel into an isolated target, and imports the installed src.rag modules successfully.
• npm.cmd test — 62 passed; compileall and the Windows offscreen source smoke passed.
• git diff --check passed.

A previous Windows native-DLL/Application-Control import block remains unexplained. The current package import test passes in this environment; this PR does not claim to fix the host policy. The standard Python 3.10–3.12, Linux/macOS, and PWA GitHub checks remain the merge gate.

[github-actions]

Welcome! 👋 Thanks for your first pull request in this repository.

A maintainer will review it soon. Please make sure:

• Your changes are tested
• Documentation is updated if needed
• The PR description explains what and why

Thanks for contributing!