feat(dx): pre-commit hooks for local CI (no remote needed)

Local quality gate that runs on every git commit:
- node --check syntax on staged .js files
- block on new emoji in staged .js/.html/.css (md files allowed)
- block on new console.log/debug/debugger statements
- backend route auth lint (existing npm run lint:routes)
- backend tests (baseline 3 fails, block if grew)

Install: npm run hooks:install (top-level)
Bypass: git commit --no-verify

Skips slow checks when irrelevant files changed (tests/lint only run
if backend touched).

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

scripts/install-hooks.cmd

@@ -0,0 +1,17 @@
+@echo off
+rem install-hooks.cmd -- installs the LearnSpace pre-commit hook on Windows
+rem Usage: scripts\install-hooks.cmd
+rem Or via npm: npm run hooks:install
+
+for /f "tokens=*" %%i in ('git rev-parse --show-toplevel') do set REPO=%%i
+set HOOK=%REPO%\.git\hooks\pre-commit
+
+(
+echo #!/bin/sh
+echo # LearnSpace pre-commit hook ^(auto-generated -- edit scripts/pre-commit.js^)
+echo REPO="$(git rev-parse --show-toplevel)"
+echo node "$REPO/scripts/pre-commit.js" ^|^| exit 1
+) > "%HOOK%"
+
+echo Pre-commit hook installed at: %HOOK%
+echo Bypass anytime with: git commit --no-verify