W7f: sweep dead/legacy/fallback leftovers after native-pipeline removal

Post-deletion cleanup (units run only on wasm):
- types.h/compiler.cpp: drop the native-era SharedUnit fields so_name,
  bin_file_name, and the opt_so_optional cache-mode plumbing (no native
  optional .so path remains). The per-unit compile lock is re-keyed from
  so_name+.lock to wasm_name+.lock (still per-unit).
- unit_info() and to_string(SharedUnit*) no longer expose .so artifact fields.
- backend.h: drop the stale "+ fallback-token gate" comment.
- Docs/comments corrected to wasm-only reality: README, tests/README,
  site/doc C++ preprocessor + error_pages + unit_info pages, site/info intro,
  site/demo/unit-browser artifact card; the Phase-5 native-vs-wasm benchmark
  harness (tests/wasm_benchmark.py) reframed for the wasm-only backend.

Audit confirmed no live references remain to so_handle, load_shared_unit,
compiler_load_shared_unit, compiler_invoke*/_cli/_websocket/_serve_http,
COMPILE_SCRIPT/COMPILE_WASM_UNITS, or the native export-symbol constants;
request_ref_handler/dv_call_handler are kept (live wasm funcref casts).

Swept via the pi agent (delegated to a gpt-5.3-codex-spark sub-model);
independently re-verified on the host: run_cli_tests --include-wasm-kill =>
87 passed, 0 failed, 0 skipped.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

scripts/compile

@@ -1,47 +0,0 @@
-#!/bin/bash
-cd "$(dirname "$0")"
-cd ..
-
-SRC_DIR="$1"
-DEST_DIR="$2"
-
-SRC_FN="$3"
-PP_FN="$4"
-SO_FN="$5"
-
-LINK_OBJECTS="$6"
-
-#echo "Source Dir: $SRC_DIR"
-#echo "Dest Dir: $DEST_DIR"
-#echo "Source File: $SRC_FN"
-#echo "Preprocessed File: $PP_FN"
-#echo "Dest File: $SO_FN"
-
-mkdir -p "$DEST_DIR" > /dev/null 2>&1
-
-export CPLUS_INCLUDE_PATH="${CPLUS_INCLUDE_PATH:+${CPLUS_INCLUDE_PATH}:}$SRC_DIR"
-
-BUILDMODE="debug"
-OPT_FLAG="O0"
-
-COMPILER="clang++"
-#COMPILER="g++"
-FLAGS="-shared -g -rdynamic -w -Wall -$OPT_FLAG -std=c++20 -fpermissive -ffast-math -fPIC -Isrc/lib"
-
-LIBS="-ldl -lm -lpthread"
-SRCFLAGS="-D PLATFORM_NAME=\"linux\""
-
-# echo "Compliling executable..."
-$COMPILER "$DEST_DIR/$PP_FN" $SRCFLAGS $FLAGS $LIBS -o "$DEST_DIR/$SO_FN"
-
-# separate .o file
-#$COMPILER -c "$DEST_DIR/$PP_FN" $SRCFLAGS $FLAGS $LIBS -o "$DEST_DIR/$PP_FN.o"
-#$COMPILER "$DEST_DIR/$PP_FN.o" "$LINK_OBJECTS" $SRCFLAGS $FLAGS $LIBS -o "$DEST_DIR/$SO_FN"
-
-if [ $? -eq 0 ]
-then
-	# ls -lh "$DEST_DIR"
-	exit 0
-else
-	exit 1
-fi

scripts/compile_wasm_unit

@@ -21,9 +21,9 @@ COMMON_FLAGS=(
 	--target=wasm32-wasip1
 	-fPIC -fvisibility=default -fvisibility-inlines-hidden
 	-O1 -g -std=c++20
-	# -w as in scripts/compile: warnings are not failures. The server captures
-	# this script's output and treats any non-empty result as a compile failure
-	# (then drops the .wasm), so a successful build must be silent.
+	# The server captures this script's output and treats any non-empty result as
+	# a compile failure (then drops the .wasm), so a successful build must be
+	# silent; warnings are intentionally suppressed.
 	-w
 	# must match the core build ABI: units with RTTI/EH enabled import
 	# typeinfo/unwind symbols the -fno-rtti/-fno-exceptions core cannot provide

scripts/wasm/build_w2_units.sh

@@ -20,21 +20,12 @@ fi
 count=0
 checked=0
 skipped=0
-# Native-only units that cannot be wasm side modules (yet).
-# - error-reporting.uce deliberately throws to exercise the native exception
-#   path; the wasm backend replaces that machinery with traps (§11.1).
-# - tests/zip.uce uses try/catch around the zip library, which is carved out
-#   of the wasm core until it moves behind a hostcall (W4+ membrane work).
-SKIP_PATTERN=${UCE_W2_SKIP:-(error-reporting|tests/zip)\.uce$}
 
 for unit in "${UNITS[@]}"; do
 	case "$unit" in
 		*.uce|*.ws.uce) ;;
 		*) continue ;;
 	esac
-	if [[ "$unit" =~ $SKIP_PATTERN ]]; then
-		continue
-	fi
 	src_dir=$(dirname "$unit")
 	base=$(basename "$unit")
 	dest_dir="$BIN_DIR$src_dir"