refactor: Overhaul build system for reliability and future portability

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.

Makefile

@@ -1,14 +1,94 @@
-IMAGE_NAME := docker-aseprite
+# --- OS Detection ---
+# Attempt to detect host OS family. Fallback to 'arch'.
+# This logic checks /etc/os-release for ID or ID_LIKE fields.
+# Use $(strip ...) to remove potential leading/trailing whitespace from shell output.
+DETECTED_DISTRO := $(strip $(shell \
+    if [ -f /etc/os-release ]; then \
+        . /etc/os-release; \
+        if echo "$$ID$$ID_LIKE" | grep -q -e arch; then \
+            echo arch; \
+        elif echo "$$ID$$ID_LIKE" | grep -q -e debian -e ubuntu; then \
+            echo debian; \
+        elif echo "$$ID$$ID_LIKE" | grep -q -e fedora; then \
+            echo fedora; \
+        else \
+            echo arch; \
+        fi; \
+    else \
+        echo arch; \
+    fi \
+))
 
-build: build-image
-	docker run --rm \
-	-v ${PWD}/output:/output \
-	-v ${PWD}/dependencies:/dependencies \
-	${IMAGE_NAME}
+# Set default TARGET_DISTRO based on detection, allowing user override
+TARGET_DISTRO ?= $(DETECTED_DISTRO)
 
-build-compose:
-	docker-compose build
-	docker-compose up
+# --- Configuration ---
+IMAGE_NAME := docker-aseprite-${TARGET_DISTRO}
+DOCKERFILE := Dockerfile.${TARGET_DISTRO}
+OUTPUT_DIR := ${PWD}/output
+TARGET_DIR_IN_IMAGE := /target/aseprite/build/bin
 
+# --- Main Targets ---
+# Default target
+all: build
+
+# Prepare source files by running the script
+# Use .PHONY to ensure it always runs if called directly
+.PHONY: prepare-sources
+prepare-sources:
+	@echo "--- Preparing sources ---"
+	@./prepare_sources.sh
+
+# Build the Docker image for the target distribution
+# Depends on sources being ready (though prepare-sources isn't a file dependency)
 build-image:
-	docker build -t ${IMAGE_NAME} .
+# --- DEBUGGING ---
+	@echo "DEBUG: TARGET_DISTRO='${TARGET_DISTRO}'"
+	@echo "DEBUG: DOCKERFILE='${DOCKERFILE}'"
+# --- END DEBUGGING ---
+ifeq (,$(wildcard ${DOCKERFILE}))
+	$(error Dockerfile for target distribution '${TARGET_DISTRO}' (${DOCKERFILE}) not found)
+endif
+	@echo "--- Building Docker image (${IMAGE_NAME}) using ${DOCKERFILE} ---"
+	@docker build -t ${IMAGE_NAME} -f ${DOCKERFILE} .
+
+# Extract the compiled binary from the image
+# Depends on the image being built
+.PHONY: extract-binary
+extract-binary: build-image
+	@echo "--- Extracting Aseprite binary from ${IMAGE_NAME} ---"
+	@mkdir -p ${OUTPUT_DIR}/bin
+	@CONTAINER_ID=$$(docker create ${IMAGE_NAME}) && \
+	 docker cp "$${CONTAINER_ID}:${TARGET_DIR_IN_IMAGE}/." "${OUTPUT_DIR}/bin/" && \
+	 docker rm "$${CONTAINER_ID}" > /dev/null
+	@echo "Aseprite binary extracted to ${OUTPUT_DIR}/bin"
+
+# Main build target: Prepare sources, build image, extract binary for selected distro
+.PHONY: build
+build: prepare-sources build-image extract-binary
+	@echo "--- Build complete for ${TARGET_DISTRO} ---"
+	@echo "Aseprite binary is in ${OUTPUT_DIR}/bin"
+
+# --- Specific Distribution Targets ---
+.PHONY: build-arch build-debian build-fedora
+
+# Build for Arch Linux (default if not detected otherwise)
+build-arch:
+	$(MAKE) build TARGET_DISTRO=arch
+
+# Build for Debian/Ubuntu based systems
+build-debian:
+	$(MAKE) build TARGET_DISTRO=debian
+
+# Build for Fedora based systems
+build-fedora:
+	$(MAKE) build TARGET_DISTRO=fedora
+
+# --- Utility Targets ---
+# Clean up downloaded sources and output directory
+.PHONY: clean
+clean:
+	@echo "--- Cleaning up ---"
+	@rm -rf ./src
+	@rm -rf ${OUTPUT_DIR}
+	@echo "Cleanup complete."