🐳 Create devcontainer with pinned toolchain and document build dependencies

[szmyty]

Title: 🐳 Create devcontainer with pinned toolchain and document build dependencies

---

Description

Create a fully reproducible development environment using a Dev Container.

The environment should:

• start from Ubuntu
• install all required system dependencies
• install Rust toolchain (pinned)
• install Pandoc and document toolchain dependencies
• support immediate development with zero manual setup

This ensures consistent development across:

• local machines
• GitHub Codespaces
• CI environments

---

Goals

• Provide a “ready-to-go” development environment
• Eliminate environment drift
• Pin versions for reproducibility
• Align local and CI environments

---

Requirements

---

1. DevContainer Structure

Create:

.devcontainer/
  devcontainer.json
  Dockerfile

---

2. Base Image

Use Ubuntu-based image:

mcr.microsoft.com/devcontainers/base:ubuntu

---

3. System Dependencies (APT)

Install required tools:

• pandoc
• curl
• git
• build-essential
• pkg-config
• libssl-dev
• ca-certificates

---

Version Pinning

• Pin APT packages where possible
• Use explicit versions OR document exact versions installed

---

4. Rust Toolchain Installation

Install Rust using rustup:

• install rustup via script
• install stable toolchain
• optionally pin toolchain version

---

Requirements

• install rustc
• install cargo
• configure environment:

source "$HOME/.cargo/env"

---

5. Additional Tooling

Install:

• cross (optional but recommended)
• cargo-watch (optional for dev UX)

---

6. Taskfile Dependency

Install Taskfile:

• download from official release
• pin version using specific release URL or SHA

---

7. Environment Configuration

Ensure:

• $HOME/.cargo/bin in PATH
• working directory is project root
• shell is bash

---

8. DevContainer Configuration

In devcontainer.json:

• mount workspace
• set default shell
• enable extensions (optional)

---

9. Validation

Ensure the following work inside container:

cargo build
cargo run -- build
cargo test
pandoc --version
task --version

---

10. Copilot Guidance

• Prefer deterministic installs
• Pin versions where feasible
• Keep Dockerfile readable
• Avoid unnecessary layers or complexity
• Ensure fast rebuild times

---

Acceptance Criteria

• DevContainer builds successfully
• All dependencies installed correctly
• Rust toolchain available
• Pandoc available
• Taskfile installed
• Project builds inside container
• CLI runs successfully
• Environment is reproducible

---

Notes

This container becomes the canonical development environment for Renderflow.

Future CI pipelines should mirror this setup.