Make CI fully green: fix cspell, eslint and stylelint warnings

Problem/Motivation

Three CI jobs pass with warnings on every MR (see pipeline #877836 on MR !20):

• cspell: 201 issues in 45 files: technical terms with no project dictionary (LiteLLM, Ollama, chartjs...), a few British spellings, and two leftover French strings in test code.
• eslint: 52 errors in the three js/ files (no-var, prettier formatting, undeclared Chart global...).
• stylelint: the module ships a copy of core's .stylelintrc.json whose extends cannot resolve from the module directory, so the job dies on ConfigurationError before linting anything.

Proposed resolution

• Add .cspell-project-words.txt (picked up automatically by the CI) and fix the misspellings in code comments.
• Fix the eslint errors in js/.
• Delete .stylelintrc.json so the job falls back to core's config, then fix whatever CSS violations surface.

Remaining tasks

• None. Merged in 803b057, pipeline fully green on 1.0.x.

AI assistance

Root causes identified from CI job traces and fixes implemented with AI assistance.