Add composable multi-language linting and formatting system

PostToolUse hook auto-formats files after Edit/Write/MultiEdit with
git-blob checkpoints for safe revert. Pre-commit hook for staged files.
Canonical formatter scripts for py, sh, ts, sql, json (+ symlinks for
js, yaml, md). Install and setup scripts for project opt-in.

Includes best-practices/linting.md, HOOKS.md docs, README.md, and
session log.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/install-hooks.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+# Symlink all hooks from claude-foundations/hooks/ into ~/.claude/hooks/
+# and print the settings.json configuration to add.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+HOOKS_SRC="$(cd "$SCRIPT_DIR/../hooks" && pwd)"
+HOOKS_DST="$HOME/.claude/hooks"
+
+mkdir -p "$HOOKS_DST"
+
+echo "Installing hooks from $HOOKS_SRC → $HOOKS_DST"
+echo ""
+
+for HOOK in "$HOOKS_SRC"/*.sh; do
+    NAME="$(basename "$HOOK")"
+    ln -sf "$HOOK" "$HOOKS_DST/$NAME"
+    echo "  ✓ $NAME"
+done
+
+echo ""
+echo "Hooks symlinked. Ensure your ~/.claude/settings.json includes:"
+echo ""
+cat <<'EOF'
+{
+  "hooks": {
+    "PreCompact": [
+      {
+        "matcher": "auto",
+        "hooks": [{ "type": "command", "command": "~/.claude/hooks/pre-compact-backup.sh", "timeout": 15, "statusMessage": "Backing up transcript before compaction..." }]
+      },
+      {
+        "matcher": "manual",
+        "hooks": [{ "type": "command", "command": "~/.claude/hooks/pre-compact-backup.sh", "timeout": 15, "statusMessage": "Backing up transcript before compaction..." }]
+      }
+    ],
+    "PostToolUse": [
+      {
+        "matcher": "Edit|Write|MultiEdit",
+        "hooks": [{ "type": "command", "command": "~/.claude/hooks/post-edit-lint.sh", "timeout": 30, "statusMessage": "Formatting and linting..." }]
+      }
+    ]
+  }
+}
+EOF