docs: add initial README and OpenSpec proposal

Add comprehensive README.md documenting project purpose, architecture,
tech stack, and development workflow. Includes OpenSpec proposal
(add-initial-readme) with project documentation specification.

The README describes current state only (early development phase) and
serves as entry point for developers and AI assistants.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

openspec/changes/add-initial-readme/proposal.md

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+# Add Initial README
+
+## Why
+The project currently has no README.md file. According to `openspec/project.md`, we maintain a README.md as the primary project documentation and entry point for developers and AI assistants. A README is essential for anyone discovering this repository on Codeberg.
+
+## What Changes
+- Add README.md to project root describing current state
+- Document the project's purpose and vision
+- Explain OpenSpec-based development workflow
+- Provide setup instructions for contributors
+- **Note**: README describes *current* state only, not planned features
+
+## Impact
+- Affected specs: project-documentation (new capability)
+- Affected code: None (documentation only)
+- No breaking changes

openspec/changes/add-initial-readme/specs/project-documentation/spec.md

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+# Project Documentation Specification
+
+## ADDED Requirements
+
+### Requirement: README File
+The project root SHALL contain a README.md file that serves as the primary entry point for developers and AI assistants.
+
+#### Scenario: Repository discovery
+- **WHEN** a developer or AI assistant discovers the repository
+- **THEN** they can read README.md to understand project purpose and current state
+
+### Requirement: Current State Documentation
+The README.md SHALL accurately describe only the current implementation state, not planned features.
+
+#### Scenario: Accurate project status
+- **WHEN** reading the README.md
+- **THEN** it reflects what is actually implemented
+- **AND** does not promise or describe unimplemented features
+
+### Requirement: Getting Started Guide
+The README.md SHALL include instructions for contributors to get started with development.
+
+#### Scenario: New contributor onboarding
+- **WHEN** a new contributor wants to start developing
+- **THEN** README.md provides clear setup steps
+- **AND** explains the OpenSpec-based workflow
+
+### Requirement: OpenSpec Reference
+The README.md SHALL reference the OpenSpec documentation structure for detailed specifications.
+
+#### Scenario: Finding detailed specs
+- **WHEN** a developer needs detailed technical specifications
+- **THEN** README.md directs them to the `openspec/` directory
+- **AND** explains how to read and create proposals

openspec/changes/add-initial-readme/tasks.md

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+# Implementation Tasks
+
+## 1. Documentation
+- [x] 1.1 Draft README.md content reflecting current project state
+- [x] 1.2 Include project overview and purpose
+- [x] 1.3 Document OpenSpec workflow for contributors
+- [x] 1.4 Add getting started section for contributors
+- [x] 1.5 Include license and contact information
+- [x] 1.6 Review README.md for accuracy against project.md
+
+## 2. Validation
+- [x] 2.1 Verify OpenSpec validation passes
+- [x] 2.2 Ensure README.md aligns with openspec/project.md conventions