Localize llm-note UI and align public documentation

[lukisch]

Changes

• Add a six-language GUI language menu with a per-browser saved choice; an explicit --locale takes precedence when the GUI starts. Localize CLI help and validation errors, plus GUI start/stop messages.
• Align the six README versions, security guidance, contributor instructions, dependency notes, release gate, changelog, and related-project links with the current source and package contents. Related-project listings do not imply direct integration; the § 521 BGB note remains conditional and does not decide applicability or liability.

Validation

• Integrated care suite: 38 tests passed on the runtime patch. After the final documentation/link updates, tests/test_metadata.py passed 11/11.
• git diff --check is clean.
• Final local build: wheel SHA-256 16d3e809db76e8be91bebfc3636d940fabc0902186afde3046a1e7dac952f4c8; sdist SHA-256 efd0e93ef61123061f7b6bb8d328a9fbd0ca2a18bdb2f41c3df23a761685c39b. The wheel's 13 package files match source; all 58 sdist source files match the care tree.

The package version remains 1.0.5. No release or upload was made. Reciprocal links in other repositories are tracked separately and are not claimed complete by this PR.