Remove dashes from documentation and component text

[Irozuku]

Summary

Removed all dashes used as prose punctuation across the documentation and the text that feeds it. This covers em dashes and ordinary compound word hyphens (for example "built-in" became "built in", "machine-learning" became "machine learning") in the docs site content, the homepage, and the component descriptions that render into the generated component reference and the app UI. Established technical terms and acronyms (TF-IDF, n-gram, k-Nearest Neighbors, chi-squared, and similar), code identifiers, CLI flags, route slugs, file paths, and German compound nouns were intentionally left untouched. Both English and Spanish locales were updated.

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Type of Change

Check all that apply like this [x]:

• Backend change
• Frontend change
• CI / Workflow change
• Build / Packaging change
• Bug fix
• Documentation

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Changes (by file)

• docs/docs/**/*.md(x) and docs/i18n/es/**/*.md: rewrote prose to drop em dashes and compound hyphens across the discover, learn (tutorials and guides), deep dive, and build sections, in English and Spanish.
• docs/src/pages/index.js, docs/i18n/es/docusaurus-plugin-content-pages/index.js: removed dashes from rendered homepage strings.
• docs/src/css/custom.css, docs/src/components/HomeIcons.js, docs/src/theme/DocSidebar/Desktop/index.js: cleaned dash usage in theme text and comments.
• docs/scripts/generate_components.py: use a plain ASCII hyphen as the empty table cell placeholder so regenerated component pages stay dash free.
• DashAI/back/converters/**, DashAI/back/models/**, DashAI/back/metrics/**, DashAI/back/exploration/**, DashAI/back/explainability/**, DashAI/back/dataset_sources/**, DashAI/back/dataloaders/**, DashAI/back/job/**: removed dashes from component DISPLAY_NAME, DESCRIPTION, and schema field description text plus class and method docstrings. These strings render in the docs and the app UI.
• DashAI/back/api/**, DashAI/back/types/**, DashAI/back/services/**, DashAI/back/dependencies/**, DashAI/back/pipeline/**: removed dashes from internal code comments and docstrings only.