Adoption hardening: task docs, metadata, and JSR quality gates

[Ismail-elkorchi]

What changed for users

• Added task-oriented docs for fragment parsing, visible-text extraction, traversal, parser limits, and the parsing-versus-sanitization boundary.
• Tightened the public front door so the README, docs index, package metadata, and JSR overview now describe the same HTML parsing surface.
• Switched npm-facing README documentation links to absolute GitHub URLs and kept the user docs map free of maintainer pages.

Generated docs / docblocks

• Kept the JSR overview and public entrypoint wording aligned with the package purpose.
• Verified the selected public surfaces with the existing JSR docs quality gate.

Biggest adoption blocker fixed

• First-time users no longer have to guess whether the package is for fragment parsing, visible-text extraction, or structural traversal.

Verification commands

• npm ci
• env -u NODE_OPTIONS volta run --node 20 npm run check:fast
• env -u NODE_OPTIONS volta run --node 22 npm run check:fast
• npm run check:fast
• npm run docs:lint:jsr
• npm run docs:test:jsr
• npm run examples:run
• npm run docs:quality:jsr
• npm pack --dry-run

Manual operator steps

• None.