fix(linkedin): normalize timeline text

[gauravsaxena1997]

What and why

The existing LinkedIn timeline adapter can return noisy post text because LinkedIn activity cards repeat author/headline/timestamp fragments inside the same visible card. That makes the command harder for agents to consume when they only need clean post text and stable counters.

This PR tightens the extraction while preserving the existing command surface.

What this PR does

Updates the existing Strategy.COOKIE LinkedIn browser adapter:

opencli linkedin timeline -f json

Implementation details:

• Adds shared LinkedIn helpers for text normalization and repeated-text compaction
• Cleans duplicated author/headline fragments from extracted timeline rows
• Keeps the existing timeline command shape and columns intact
• Preserves read-only behavior and authenticated browser-session requirements

Live verification

Verified against a logged-in LinkedIn profile session. Timeline rows returned cleaner visible activity text while preserving reaction/comment/repost counters.

Checklist

• npm run build
• npx vitest run --project adapter clis/linkedin/timeline.test.js
• npm run typecheck
• node scripts/check-typed-error-lint.mjs
• node scripts/check-silent-column-drop.mjs

[jackwener]

Closed as superseded by consolidated PR #1731, merged as b6965a5.

[jackwener]

Superseded by consolidated PR #1731 (merged as b6965a5).