P5.5: migrate the 35 BuildOptions accessors off #compiler to VM-native abi(.compiler)

`BuildOptions :: struct #compiler { ...35 methods... }` becomes
`BuildOptions :: struct { }` (an opaque null-sentinel handle) plus 35 free
`ufcs (self: BuildOptions, …) abi(.compiler)` decls in build.sx, each serviced
by a new `comptime_vm.callBuildOptionFn` arm (off `callCompilerFn`). No legacy
`compiler_lib` handler: the names are registered in `bound_fns` with a single
bailing stub only so `weldedCompilerFn` accepts them.

- String lifetime: setters dupe the arg into the persistent `Vm.gpa` (the
  Compilation allocator, threaded into both `tryEval` and `runBuildCallback` —
  not the per-eval VM arena) and write/append to the threaded `BuildConfig`.
  Getters read the field/slice or compute the target predicate from the triple.
- Dispatch routing (Option B): a `#run`/const-init entry that directly calls a
  compiler-domain/welded fn (`emit_llvm.entryNeedsVm`) runs on the VM with no
  legacy fallback regardless of the `-Dcomptime-flat` gate, so gate-OFF stays
  green without a legacy BuildOptions handler (P5.7 retires the legacy interp).
- Mark the 5 `platform/bundle.sx` getter-calling helpers `abi(.compiler)` (they
  are comptime-only bundler code; otherwise their now-welded getter calls trip
  the runtime-call gate).
- 37 `.ir` snapshots regenerated (std transitively imports build.sx → string-
  pool/type-table indices shift); verified `.ir`-only, zero behavior-stream diffs.

BuildOptions `compiler_call` strict bails gone (1609/1614/1615 strict-clean);
1616 now bails on a separate, pre-existing unported bitwise/shift VM gap (`shr`),
to port first in P5.6. 703/0 both gates.

Also sweep the outdated "flat memory" terminology to "comptime/byte-addressable"
across comptime_vm + the plan/checkpoint/CLAUDE docs: the comptime VM is
arena-backed, byte-addressable memory where `Addr` is a real host pointer, not a
flat contiguous address space (flag names `-Dcomptime-flat`/`SX_COMPTIME_FLAT` kept).

library/modules/platform/bundle.sx

@@ -223,7 +223,7 @@ IOS_MIN_OS : string : "14.0";
 // carry the keys the iOS launcher needs (UIDeviceFamily,
 // LSRequiresIPhoneOS, UIApplicationSceneManifest, DTPlatformName,
 // MinimumOSVersion); macOS doesn't need any of those.
-build_info_plist :: (opts: BuildOptions, exe_name: string, bundle_id: string) -> string {
+build_info_plist :: (opts: BuildOptions, exe_name: string, bundle_id: string) -> string abi(.compiler) {
     if opts.is_ios() {
         platform_key := if opts.is_ios_simulator() then "iPhoneSimulator" else "iPhoneOS";
         return format(#string PLIST
@@ -371,7 +371,7 @@ copy_asset_dir :: (src: string, dest: string, bundle: string) -> bool {
 // paths into `<dest_dir>`. Walks the framework paths in order; first
 // hit wins. Falls back to a `cp -R` subprocess because fs.sx Phase 1A
 // doesn't expose `list_dir` / `walk` yet.
-embed_framework :: (opts: BuildOptions, name: string, dest_dir: string) -> bool {
+embed_framework :: (opts: BuildOptions, name: string, dest_dir: string) -> bool abi(.compiler) {
     subdir := concat(name, ".framework");
     path_count := opts.framework_path_count();
     i : i64 = 0;
@@ -580,7 +580,7 @@ absolutify :: (path: string) -> string {
     path
 }
 
-android_bundle_main :: (opts: BuildOptions, binary: string, apk_path: string, bundle_id: string) -> bool {
+android_bundle_main :: (opts: BuildOptions, binary: string, apk_path: string, bundle_id: string) -> bool abi(.compiler) {
     // The bundler `cd`s into the stage dir for `zip` steps, so any
     // relative path the caller gave us would resolve against the wrong
     // cwd. Pin everything to absolute paths up front.
@@ -872,7 +872,7 @@ lib_name_from_so_basename :: (basename: string) -> string {
 // `android:hasCode="true"` so Android loads the bundled classes.dex.
 // Otherwise it falls back to the legacy NativeActivity shape with an
 // `android.app.lib_name` meta-data entry pointing at the .so.
-build_android_manifest :: (opts: BuildOptions, package: string, lib_name: string) -> string {
+build_android_manifest :: (opts: BuildOptions, package: string, lib_name: string) -> string abi(.compiler) {
     pkg_esc := xml.escape(package);
     lib_esc := xml.escape(lib_name);
     if opts.jni_main_count() > 0 {
@@ -969,7 +969,7 @@ dir_part :: (path: string) -> string {
 // the resulting class files via `d8 --release --lib <android.jar>
 // --output <stage>` so `<stage>/classes.dex` lands where the
 // orchestrator can zip it into the APK.
-compile_jni_main_sources :: (opts: BuildOptions, stage: string, android_jar: string, d8_path: string) -> bool {
+compile_jni_main_sources :: (opts: BuildOptions, stage: string, android_jar: string, d8_path: string) -> bool abi(.compiler) {
     java_root := path_join(stage, "java");
     classes_root := path_join(stage, "classes");
     if !create_dir_all(str_to_cstr(java_root)) {