docs: add badges, table of contents, missing skills, and prerequisites

[Gingiris]

What this PR does

Improves the README with better discoverability and completeness.

Why

• New visitors benefit from badges showing project activity at a glance
• The skill list has grown to 13 entries — a Table of Contents helps navigation
• Three recently merged skills (autobrowse, company-research, event-prospecting) are present in skills/ but missing from the README table
• A "Prerequisites" section reduces friction for first-time users who may not know what they need installed

Changes

• Added GitHub stars, last commit, and license badges
• Added a Table of Contents section with anchor links
• Added autobrowse, company-research, and event-prospecting to the skills table
• Added a "Prerequisites" section listing Node.js 18+, Chrome, and optional Browserbase account

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🤖 This PR was created with AI assistance and reviewed by a human.

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Note

Low Risk
Low risk documentation-only update; no runtime code or behavior changes.

Overview
Improves README.md discoverability by adding GitHub/License badges and a Table of Contents.

Updates the Skills table to include autobrowse, company-research, and event-prospecting, and adds a new Prerequisites section listing required Node.js/Chrome and an optional Browserbase account.

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