docs: fill out compat, lvglh, and toolchain documentation

Replace placeholder content in doc/compat/, doc/lvglh/, and
doc/toolchain/ with comprehensive documentation derived from the
source files.

- compat: document Wasuro WASM VM compatibility shims
- lvglh: document LVGL v9.2.2 configuration, fonts, and patches
- toolchain: document all 13 build pipeline scripts

doc/toolchain/compile.md

@@ -1 +1,44 @@
-# Placeholder
+# compile.sh
+
+Top-level build orchestrator for the Asuro kernel.
+
+## Overview
+
+`compile.sh` is the main entry point for building the Asuro operating system. It sequentially invokes each stage of the build pipeline, halting on the first failure. After all stages complete (or a failure occurs), it calls `compile_finish.sh` to generate a build-status badge and set the exit code.
+
+## Prerequisites
+
+- All sub-scripts must be present in the same directory as `compile.sh`.
+- The Docker build container must provide: `bash`, `nasm`, `fpc`, `gcc`, `ld`, `grub-mkrescue`, `git`, `wget`, and standard POSIX utilities.
+
+## Inputs
+
+None directly. Each sub-script reads its own inputs from the source tree.
+
+## Outputs
+
+- All artifacts produced by the sub-scripts (object files, kernel binary, ISO image, version info, badges, documentation).
+- Final exit code: `0` on success, `1` on failure.
+
+## Behavior
+
+1. Clears the `lib/` directory to ensure a clean build.
+2. Defines a helper function `runOrFail` that runs a command and increments `ERRCOUNT` on failure.
+3. Resolves its own directory (`TOOLCHAIN_DIR`) so sub-scripts can be located by absolute path.
+4. Declares an ordered list of build steps (script name and error message pairs):
+   - `compile_stub.sh` -- Assemble boot stubs.
+   - `compile_vergen.sh` -- Generate version information.
+   - `compile_lvgl.sh` -- Compile the LVGL graphics library.
+   - `compile_wasuro.sh` -- Pull the Wasuro WASM runtime sources.
+   - `compile_sources.sh` -- Compile Free Pascal kernel sources.
+   - `compile_link.sh` -- Link all object files into `kernel.bin`.
+   - `compile_isogen.sh` -- Create the bootable ISO image.
+   - `compile_docs.sh` -- Generate project documentation.
+5. Iterates through the steps. If `ERRCOUNT` is non-zero, all remaining steps are skipped.
+6. Calls `compile_finish.sh` with either `"success"` or `"failed"` depending on whether any errors were recorded.
+7. Changes directory back up one level (`cd ..`).
+
+## Notes
+
+- `compile_finish.sh` is sourced (`. script`) rather than executed as a sub-process, so its `exit` call terminates the entire pipeline.
+- The build is fail-fast: the first failing step prevents all subsequent steps from running, but the finish step always runs to produce a status badge.