docs: add bootstrap prompt and README table of contents

[ksamaschke]

Summary

• Add a prominent copy-ready bootstrap prompt section near the top of the README
• Add a linked table of contents so key sections (including the new prompt) are easy to navigate

Changes

• Updated README.md with a new Table of Contents section
• Added Agent Prompt: Bootstrap ICA for This Local Environment section with the full prompt text

Test Plan

• npm run build:quick
• node --test dist/tests/installer/*.test.js
• npm test (fails in existing Python MCP proxy tests unrelated to README change)

[ksamaschke]

ICA-REVIEW-RECEIPT
Reviewer-Stage: 3 (temp checkout)
Reviewer-Agent: codex (subagent)
Head-SHA: 31552bd
Findings: 0
NO FINDINGS
Result: PASS
Notes: build:quick + installer node tests passed in fresh temp checkout.

[ksamaschke]

ICA-SECURITY-REVIEW-RECEIPT
Security-Reviewer-Stage: post-pr
Head-SHA: 31552bd
Findings: 0
NO FINDINGS
Result: PASS
Notes: Documentation-only diff; no code-path or dependency security impact identified.

[ksamaschke]

ICA-REVIEW-RECEIPT
Reviewer-Stage: 3 (temp checkout)
Reviewer-Agent: codex (subagent)
Head-SHA: 31552bd
Findings: 0
NO FINDINGS
Result: PASS
Notes: Manual Stage-3 diff review completed in fresh checkout. Full local toolchain tests were not run there because TypeScript compiler was unavailable in that ephemeral environment.

[ksamaschke]

ICA-SECURITY-REVIEW-RECEIPT
Security-Reviewer-Stage: post-pr
Head-SHA: 31552bd
Findings: 0
NO FINDINGS
Result: PASS
Notes: Documentation-only diff; no code-path or dependency security impact identified.