fix: resolve Claude Code Bash hook "cannot execute binary file" on Windows

Root cause in ~/.claude/settings.local.json (user-global):
1. UTF-8 BOM + CRLF line endings left by patch_settings_cl_v2_simple.ps1
2. Double-wrapped command "\"bash.exe\" \"wrapper.sh\"" broke Windows
   argument splitting on the space in "Program Files", making bash.exe
   try to execute itself as a script.

Fix:
- Rewrite settings.local.json as UTF-8 (no BOM), LF, with the hook command
  pointing directly at observe-wrapper.sh and passing "pre"/"post" as a
  positional arg so HOOK_PHASE is populated correctly in observe.sh.

Docs:
- docs/fixes/HOOK-FIX-20260421.md — full root-cause analysis.
- docs/fixes/apply-hook-fix.sh — idempotent applier script.

docs/fixes/apply-hook-fix.sh

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+# Apply ECC hook fix to ~/.claude/settings.local.json.
+#
+# - Creates a timestamped backup next to the original.
+# - Rewrites the file as UTF-8 (no BOM), LF line endings.
+# - Routes hook commands directly at observe-wrapper.sh with a "pre"/"post" arg.
+#
+# Related fix doc: docs/fixes/HOOK-FIX-20260421.md
+
+set -euo pipefail
+
+TARGET="${1:-$HOME/.claude/settings.local.json}"
+WRAPPER="${ECC_OBSERVE_WRAPPER:-$HOME/.claude/skills/continuous-learning/hooks/observe-wrapper.sh}"
+
+if [ ! -f "$WRAPPER" ]; then
+  echo "[hook-fix] wrapper not found: $WRAPPER" >&2
+  exit 1
+fi
+
+mkdir -p "$(dirname "$TARGET")"
+
+if [ -f "$TARGET" ]; then
+  ts="$(date +%Y%m%d-%H%M%S)"
+  cp "$TARGET" "$TARGET.bak-hookfix-$ts"
+  echo "[hook-fix] backup: $TARGET.bak-hookfix-$ts"
+fi
+
+# Convert wrapper path to forward-slash form for JSON.
+wrapper_fwd="$(printf '%s' "$WRAPPER" | tr '\\\\' '/')"
+
+# Write the new config as UTF-8 (no BOM), LF line endings.
+printf '%s\n' '{
+  "hooks": {
+    "PreToolUse": [
+      {
+        "matcher": "*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "'"$wrapper_fwd"' pre"
+          }
+        ]
+      }
+    ],
+    "PostToolUse": [
+      {
+        "matcher": "*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "'"$wrapper_fwd"' post"
+          }
+        ]
+      }
+    ]
+  }
+}' > "$TARGET"
+
+echo "[hook-fix] wrote: $TARGET"
+echo "[hook-fix] restart the claude CLI for changes to take effect"