docs: update README and AGENTS.md

[betegon]

closes #46

Summary

Rewrites the README to be user-focused with a clear separation between usage and development. Updates AGENTS.md with project goals and accurate architecture documentation.

Changes

README.md

• Adds banner image at the top
• Prioritizes curl install script as the recommended method
• Highlights key features: DSN auto-detection, Seer AI integration, monorepo support
• Includes commands table with all command groups
• Separates development section at the bottom
• Links to cli.sentry.dev for full documentation

AGENTS.md

• Adds project overview with goals and key features
• Updates architecture section with complete directory structure:
  • lib/db/ - SQLite database layer
  • lib/dsn/ - DSN detection with language support
  • lib/formatters/ - Output formatting
• Updates file locations table with Seer types and DSN language paths

Test plan

Visual review - these are documentation-only changes.

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

📋 Changelog Preview

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Bug Fixes 🐛

• (telemetry) Capture command errors to Sentry by betegon in #145

Documentation 📚

• Update README and AGENTS.md by betegon in #148

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_{🤖 This preview updates automatically when you update the PR.}

[BYK]

Suggested change

	- **Fast** - Native binaries via Bun, SQLite caching for API responses
	- **Fast** - Native binaries via Bun

We do NOT cache API responses at all 😅