WIP: wasm compatible patcher?

wip/wasm-feasibility.md

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+# WASM Feasibility — Confirmed
+
+## Test Results
+
+All kobopatch tests pass under both native and WASM targets.
+
+### Native (`go test ./...`)
+```
+ok   github.com/pgaskin/kobopatch/kobopatch            0.003s
+ok   github.com/pgaskin/kobopatch/patchfile/kobopatch   0.003s
+ok   github.com/pgaskin/kobopatch/patchfile/patch32lsb  0.002s
+ok   github.com/pgaskin/kobopatch/patchlib              0.796s
+```
+
+### WASM (`GOOS=js GOARCH=wasm`, run via Node.js)
+```
+ok   github.com/pgaskin/kobopatch/kobopatch            0.158s
+ok   github.com/pgaskin/kobopatch/patchfile/kobopatch   0.162s
+ok   github.com/pgaskin/kobopatch/patchfile/patch32lsb  0.133s
+ok   github.com/pgaskin/kobopatch/patchlib              9.755s
+```
+
+### Notes
+
+- `patchlib` tests are ~12x slower under WASM (9.7s vs 0.8s) — expected overhead
+- All pure Go dependencies compile to WASM without issues
+- No CGO, no OS-specific syscalls in the core libraries
+- Go WASM executor: `$(go env GOROOT)/lib/wasm/go_js_wasm_exec`
+- Node.js v25.8.1 used for WASM test execution
+
+## What Works in WASM
+
+- Binary patching (`patchlib`)
+- ARM Thumb-2 instruction assembly (`patchlib/asm`)
+- ELF symbol table parsing (`patchlib/syms`)
+- YAML patch format parsing (`patchfile/kobopatch`)
+- Binary patch format parsing (`patchfile/patch32lsb`)
+- CSS parsing (`patchlib/css`)
+- Zlib compression/decompression
+- tar.gz reading/writing
+- ZIP extraction
+
+## What Won't Work in WASM (and doesn't need to)
+
+- `os.Open` / `os.Create` — replace with in-memory I/O
+- `os.Chdir` — not needed, use in-memory paths
+- `exec.Command` (lrelease for translations) — skip, rare use case
+- `ioutil.TempDir` — not needed with in-memory approach