fix(app): Normalize provisioning templates and Clerk props

Use autoescape for Jinja rendering to satisfy bandit checks and\nremove deprecated Clerk SignInButton props to restore type checks.\nAlso ignore tsbuildinfo artifacts and tidy boot instructions.\n\nCo-Authored-By: Claude <noreply@anthropic.com>

frontend/src/app/boards/[boardId]/page.tsx

@@ -172,8 +172,6 @@ export default function BoardDetailPage() {
           <p className="text-sm text-muted">Sign in to view boards.</p>
           <SignInButton
             mode="modal"
-            afterSignInUrl="/boards"
-            afterSignUpUrl="/boards"
             forceRedirectUrl="/boards"
             signUpForceRedirectUrl="/boards"
           >

frontend/src/app/boards/new/page.tsx

@@ -70,8 +70,6 @@ export default function NewBoardPage() {
           <p className="text-sm text-muted">Sign in to create a board.</p>
           <SignInButton
             mode="modal"
-            afterSignInUrl="/boards/new"
-            afterSignUpUrl="/boards/new"
             forceRedirectUrl="/boards/new"
             signUpForceRedirectUrl="/boards/new"
           >

frontend/src/app/boards/page.tsx

@@ -112,8 +112,6 @@ export default function BoardsPage() {
           <p className="text-sm text-muted">Sign in to view boards.</p>
           <SignInButton
             mode="modal"
-            afterSignInUrl="/boards"
-            afterSignUpUrl="/boards"
             forceRedirectUrl="/boards"
             signUpForceRedirectUrl="/boards"
           >