Remove Node.js hooks, require ots CLI only

- Delete hooks/post-commit-node (local proofs only, no attestation)
- Delete hooks/pre-commit-node (no upgrade support)
- Update hooks/install.sh to require ots CLI (no fallback)
- Update documentation with clear ots CLI requirement
- Add prominent warnings about Node.js limitations

Rationale: The @opentimestamps/ots Node.js package only creates
local proofs without calendar submission or Bitcoin attestation.
For tamper-evident timestamps, ots CLI is the only complete
implementation. No partial/fallback implementations.

hooks/install.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 # Git OpenTimestamp Hooks Installer
-# Detects available tools and installs matching hooks
+# Requires: opentimestamps-client (ots CLI)
 
 set -e
 
@@ -14,44 +14,35 @@ if ! git rev-parse --git-dir > /dev/null 2>&1; then
     exit 1
 fi
 
-HOOKS_DIR="$(git rev-parse --git-dir)/hooks"
-MODE=""
-
-# Detect available tools
-if command -v ots &> /dev/null; then
-    MODE="ots"
-    echo "Detected: ots CLI"
-elif command -v node &> /dev/null && node -e "require('@opentimestamps/ots')" &> /dev/null 2>&1; then
-    MODE="node"
-    echo "Detected: @opentimestamps/ots (Node.js)"
-    echo "Note: Node version creates local proofs only (no calendar submission)"
-    echo ""
-    
-    # Install node package locally if not already present
-    if [ ! -d "node_modules/@opentimestamps" ]; then
-        echo "Installing @opentimestamps/ots locally..."
-        npm install @opentimestamps/ots
-        echo "✓ Package installed"
-    fi
-else
-    echo "Error: Neither ots CLI nor @opentimestamps/ots found" >&2
-    echo "Install one of:" >&2
-    echo "  pipx install opentimestamps-client  (recommended)" >&2
-    echo "  npm install @opentimestamps/ots     (local proofs only)" >&2
+# Check for ots CLI (required)
+if ! command -v ots &> /dev/null; then
+    echo "Error: ots CLI not found" >&2
+    echo "" >&2
+    echo "OpenTimestamp client is required for full Bitcoin attestation." >&2
+    echo "Install with one of:" >&2
+    echo "" >&2
+    echo "  # Recommended (isolated install)" >&2
+    echo "  pipx install opentimestamps-client" >&2
+    echo "" >&2
+    echo "  # Or with pip" >&2
+    echo "  pip install opentimestamps-client" >&2
+    echo "" >&2
+    echo "  # Or from source" >&2
+    echo "  git clone https://github.com/opentimestamps/opentimestamps-client" >&2
+    echo "  cd opentimestamps-client && pip install ." >&2
+    echo "" >&2
     exit 1
 fi
 
-echo ""
-echo "Installing $MODE hooks to: $HOOKS_DIR"
+echo "✓ Detected: ots CLI ($(ots --version))"
 
-# Copy appropriate hooks
-if [ "$MODE" = "ots" ]; then
-    cp "$SCRIPT_DIR/post-commit-ots" "$HOOKS_DIR/post-commit"
-    cp "$SCRIPT_DIR/pre-commit-ots" "$HOOKS_DIR/pre-commit"
-else
-    cp "$SCRIPT_DIR/post-commit-node" "$HOOKS_DIR/post-commit"
-    cp "$SCRIPT_DIR/pre-commit-node" "$HOOKS_DIR/pre-commit"
-fi
+HOOKS_DIR="$(git rev-parse --git-dir)/hooks"
+
+echo "Installing hooks to: $HOOKS_DIR"
+
+# Copy ots hooks
+cp "$SCRIPT_DIR/post-commit-ots" "$HOOKS_DIR/post-commit"
+cp "$SCRIPT_DIR/pre-commit-ots" "$HOOKS_DIR/pre-commit"
 
 chmod +x "$HOOKS_DIR/post-commit" "$HOOKS_DIR/pre-commit"
 
@@ -61,29 +52,18 @@ echo "✓ Pre-commit backfill hook installed"
 # Setup .gitignore
 GITIGNORE=".gitignore"
 if [ ! -f "$GITIGNORE" ]; then
-    cat > "$GITIGNORE" << 'EOF'
-.ots/.attestation-cache
-node_modules/
-EOF
+    echo ".ots/.attestation-cache" > "$GITIGNORE"
     echo "✓ Created .gitignore"
 elif ! grep -q ".ots/.attestation-cache" "$GITIGNORE"; then
     echo ".ots/.attestation-cache" >> "$GITIGNORE"
-    if [ "$MODE" = "node" ] && ! grep -q "node_modules/" "$GITIGNORE"; then
-        echo "node_modules/" >> "$GITIGNORE"
-    fi
     echo "✓ Updated .gitignore"
 fi
 
 echo ""
-echo "Mode: $MODE"
-if [ "$MODE" = "ots" ]; then
-    echo "  - Full Bitcoin attestation via calendars"
-    echo "  - Proofs submitted to remote calendars"
-else
-    echo "  - Local proofs only (no calendar submission)"
-    echo "  - For full attestation, use: pipx install opentimestamps-client"
-fi
-
+echo "Configuration:"
+echo "  - Full Bitcoin attestation via remote calendars"
+echo "  - Proofs submitted to 4+ calendar servers"
+echo "  - Attestation available after ~10 min (Bitcoin confirmation)"
 echo ""
 echo "Next steps:"
 echo "1. Make a test commit"