This commit introduces a major refactoring of the Aseprite build process. It replaces the previous fragile system (prone to dependency fetching failures) with an interim multi-distribution Docker approach, paving the way for a future transition to Flatpak.
**Problems Addressed:**
* **Build Fragility & Dependency Fetching:** The prior method, compiling dependencies from source within a generic container, frequently failed due to network issues and rate limiting during source/sub-dependency acquisition (e.g., Skia's `git-sync-deps`), often late in the process. Source state inconsistencies could also cause failures.
* **Complexity of Full Source Builds:** Managing the compilation of the entire dependency tree from source was complex.
**New Architecture & Rationale:**
* **Host-Side Source Preparation (`prepare_sources.sh`):** Isolates the problematic source fetching and state management to a host-side script run *before* the main build. Key features:
* Handles cloning/updating core sources (`depot_tools`, Skia, Aseprite).
* Runs Skia `git-sync-deps` with **robust retry logic** to specifically address rate limit errors.
* Includes an `--check-integrity` flag which performs **aggressive checks and resets** (fetching, checking out specific tags/commits, resetting state) to ensure the local source directories precisely match the required state for the build, potentially involving significant network activity.
* **Distribution-Specific Builds (Interim Step):** Introduced `Dockerfile.arch`, `Dockerfile.debian`, `Dockerfile.fedora`. These use native package managers to install pre-built *common* development libraries within the container, simplifying the Docker build stage itself. Requires OS detection or manual selection (`TARGET_DISTRO`).
* **Clear Build Stages (Makefile):** Orchestrates source preparation, image building, and final binary extraction (`docker cp` to `./output/bin`).
* **Cleaned Structure:** Removed obsolete scripts/files (`compile.sh`, generic `Dockerfile`, `docker-compose.yml`) and updated `.gitignore`.
**Limitations & Future Direction (Flatpak):**
* **Fetching Challenges Persist:** While reliability is improved by isolating source prep and adding retries/integrity checks in `prepare_sources.sh`, the core challenge of potential rate limits or network issues during this initial step remains.
* **Flatpak for Portability:** The current multi-distro Docker setup is an **intermediate solution**. The ultimate goal and **forward-maintained approach** is migrating to **Flatpak (`flatpak-builder`)**. Flatpak will provide a **unified, distribution-agnostic build environment** using standard runtimes and produce a **portable `.flatpak` bundle**, eliminating the need for OS detection/separate Dockerfiles and ensuring consistent builds *after* sources are successfully prepared.
