perf(bundle): lazy-load the nunjucks template engine (#2535)

Closes #2531.

## Summary

The full `nunjucks` templating engine (~226KB) plus `ha-nunjucks`
(~46KB) — roughly **272KB, ~13% of the eager entry chunk** — was
statically imported and downloaded by every card on initial load, even
though templates only apply when a config value contains a `{{ … }}` /
`{% … %}` delimiter. Most cards use no templates and never need the
engine.

This defers the engine behind a dynamic `import('ha-nunjucks/dist')` so
it ships in a separate, on-demand chunk instead of the eager
`card-*.js`.

## Approach

The render path (`TemplateRenderer.renderRecursively`) is **kept
synchronous** — it is called from many synchronous hot paths
(condition/trigger evaluators, picture-elements rendering, actions,
folder matchers), and making it async would be a large, high-risk
refactor of the evaluation core.

Instead:

- **New `src/card-controller/templates/engine.ts`** — a module-level
singleton lazy loader (`loadTemplateEngine()` / `getTemplateEngine()`)
shared across all `TemplateRenderer` instances, plus a
`containsTemplate()` delimiter helper.
- **Delimiter gating** — strings without a delimiter never touch the
engine (the overwhelming majority of renders).
- **Pre-warm at config time** — because every template string originates
in the config, a new mandatory `TEMPLATE_ENGINE` initialization aspect
loads the engine before first render whenever the config contains a
delimiter. This **guarantees no raw `{{ … }}` flash**: content/condition
rendering is blocked until the engine is present for template-using
cards. Cards without templates never load it.

## Result

- nunjucks + ha-nunjucks move out of the eager chunk into a separate
chunk fetched only when a card actually uses templates.
- No change to the synchronous public render API; condition/trigger
evaluation core untouched.

## Tests

- New `engine.ts` loader coverage (concurrent load, cached reuse,
not-loaded fallback).
- The 11 existing test files that render real (delimiter-bearing)
templates declare their dependency explicitly via
`beforeAll(loadTemplateEngine)` — no global/implicit setup hook.
- Full suite green (4764 tests), lint and ts-prune clean, per-file 100%
coverage maintained for the affected directories.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

https://claude.ai/code/session_016ykWemdkZrgywvC71pHc6c

---
_Generated by [Claude
Code](https://claude.ai/code/session_016ykWemdkZrgywvC71pHc6c)_

tests/card-controller/actions/actions/generated-action.test.ts

@@ -0,0 +1,77 @@
+import { describe, expect, it, vi } from 'vitest';
+
+import { GeneratedAction } from '../../../../src/card-controller/actions/actions/generated-action';
+import type { TriggerData } from '../../../../src/condition-trigger/triggers/types';
+import type { ActionGenerator } from '../../../../src/config/schema/actions/custom/generated-action';
+import { createCameraAction, createGeneratedAction } from '../../../../src/utils/action';
+import { createCardAPI } from '../../../test-utils';
+
+describe('GeneratedAction', () => {
+  it('should run the generated action as a nested action set', async () => {
+    const api = createCardAPI();
+    const generated = createCameraAction('camera.office');
+    const action = new GeneratedAction(
+      {},
+      createGeneratedAction(() => generated),
+    );
+
+    await action.execute(api);
+
+    expect(api.getActionsManager().executeNestedActions).toBeCalledWith({
+      actions: generated,
+      config: undefined,
+      triggerData: undefined,
+    });
+  });
+
+  it('should run multiple generated actions when the generator returns several', async () => {
+    const api = createCardAPI();
+    const generated = [
+      createCameraAction('camera.one'),
+      createCameraAction('camera.two'),
+    ];
+    const action = new GeneratedAction(
+      {},
+      createGeneratedAction(() => generated),
+    );
+
+    await action.execute(api);
+
+    expect(api.getActionsManager().executeNestedActions).toBeCalledWith({
+      actions: generated,
+      config: undefined,
+      triggerData: undefined,
+    });
+  });
+
+  it('should do nothing when the generator produces nothing', async () => {
+    const api = createCardAPI();
+    const action = new GeneratedAction(
+      {},
+      createGeneratedAction(() => null),
+    );
+
+    await action.execute(api);
+
+    expect(api.getActionsManager().executeNestedActions).not.toBeCalled();
+  });
+
+  it('should pass the api and trigger data to the generator', async () => {
+    const api = createCardAPI();
+    const triggerData: TriggerData = {
+      platform: 'state',
+      entity_id: 'input_select.camera',
+    };
+    const generator: ActionGenerator = vi.fn(() => null);
+    const action = new GeneratedAction(
+      {},
+      createGeneratedAction(generator),
+      undefined,
+      triggerData,
+    );
+
+    await action.execute(api);
+
+    expect(generator).toBeCalledWith({ api, triggerData });
+  });
+});

tests/card-controller/actions/actions/if.test.ts

@@ -35,7 +35,7 @@ describe('IfAction', () => {
 
     await action.execute(api);
 
-    expect(api.getActionsManager().executeActions).toBeCalledWith({
+    expect(api.getActionsManager().executeNestedActions).toBeCalledWith({
       actions: thenActions,
       config: undefined,
       triggerData: undefined,
@@ -59,7 +59,7 @@ describe('IfAction', () => {
 
     await action.execute(api);
 
-    expect(api.getActionsManager().executeActions).toBeCalledWith({
+    expect(api.getActionsManager().executeNestedActions).toBeCalledWith({
       actions: elseActions,
       config: undefined,
       triggerData: undefined,
@@ -82,6 +82,6 @@ describe('IfAction', () => {
 
     await action.execute(api);
 
-    expect(api.getActionsManager().executeActions).not.toBeCalled();
+    expect(api.getActionsManager().executeNestedActions).not.toBeCalled();
   });
 });

tests/card-controller/actions/actions/set.test.ts

@@ -2,11 +2,20 @@ import { describe, expect, it, vi } from 'vitest';
 
 import { ActionSet } from '../../../../src/card-controller/actions/actions/set';
 import { createLogAction } from '../../../../src/utils/action';
+import { arrayify } from '../../../../src/utils/basic';
 import { createCardAPI } from '../../../test-utils';
 
 describe('ActionSet', () => {
-  it('should execute single action', async () => {
+  const createAPI = () => {
     const api = createCardAPI();
+    vi.mocked(api.getLockManager().getAllowedActions).mockImplementation((actions) =>
+      arrayify(actions),
+    );
+    return api;
+  };
+
+  it('should execute single action', async () => {
+    const api = createAPI();
 
     const set = new ActionSet({}, createLogAction('Hello, world!'));
 
@@ -16,7 +25,7 @@ describe('ActionSet', () => {
   });
 
   it('should not execute invalid action', async () => {
-    const api = createCardAPI();
+    const api = createAPI();
     const set = new ActionSet(
       {},
       createLogAction('Hello, world!', {
@@ -30,7 +39,7 @@ describe('ActionSet', () => {
   });
 
   it('should stop execution', async () => {
-    const api = createCardAPI();
+    const api = createAPI();
 
     const set = new ActionSet({}, createLogAction('Hello, world!'));