Require Playwright E2E tests in every verification step

- New skill e2e-testing: on-demand Playwright setup (config, test:e2e script), acceptance-criteria-driven specs (one per feature + app-shell smoke), blueprint-driven semantic locators, and the shared verification checklist
- /add-feature Step 7 and /execute-milestones Step 2.6 now write/update E2E specs and run npm run test:e2e alongside test/lint/typecheck; milestone gates and completion criteria include E2E
- /generate-app Step 5 sets up Playwright and creates the app-shell smoke spec for the web target (integration_test / UI automation noted for flutter/winui3)
- steering tasklist template, milestone-planning Definition of Done, milestone-execution task slicing/gates, development-guidelines pointers, and implementation-validator checks updated
- AGENTS.md and README updated

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -69,7 +69,7 @@ A fully autonomous loop, one feature per run. Each run:
 2. Reads the feature's entry in its phase file and the design spec first — and updates the design first if the feature changes the UI
 3. Implements every task in `tasklist.md`, checking items off as it goes
 4. Validates quality with the `implementation-validator` subagent
-5. Runs `npm test`, `npm run lint`, `npm run typecheck` until green
+5. Writes Playwright E2E tests for the feature's acceptance criteria, then runs `npm test`, `npm run lint`, `npm run typecheck`, and `npm run test:e2e` until green
 6. Records a retrospective, reconciles all six `docs/` documents, and checks the feature off in its phase file
 
 ### Step 8 — Repeat and maintain
@@ -79,7 +79,8 @@ A fully autonomous loop, one feature per run. Each run:
 - Document quality checks → `/review-docs <path>`
 
 **A feature is "done" when**: all tasks in its tasklist are `[x]`, validation passes,
-test/lint/typecheck succeed, and the persistent documents are back in sync with the code.
+test/lint/typecheck and the Playwright E2E suite succeed, and the persistent documents are back
+in sync with the code.
 
 ---
 
@@ -240,6 +241,7 @@ opencode
         ├── platform-ui-generation/(SKILL.md)
         ├── milestone-planning/    (SKILL.md + template.md)
         ├── milestone-execution/   (SKILL.md)
+        ├── e2e-testing/           (SKILL.md)
         └── steering/              (SKILL.md + templates/)
 ```
 
@@ -371,8 +373,8 @@ This fully autonomous workflow:
 4. Generates the steering files (planning mode of the steering skill)
 5. Implements every task in `tasklist.md`, marking each `[ ]` → `[x]` as it goes
 6. Launches the `implementation-validator` subagent for quality review
-7. Runs `npm test`, `npm run lint`, `npm run typecheck`
-8. Records a retrospective, reconciles all six persistent docs with the feature, and checks the feature off in its milestone document
+7. Writes Playwright E2E tests for the acceptance criteria, then runs `npm test`, `npm run lint`, `npm run typecheck`, `npm run test:e2e`
+8. Records a retrospective, reconciles all six persistent docs with the feature, and checks the feature off in its phase file
 
 ### 6. Execute a phase file (alternative to per-feature runs)
 
@@ -468,6 +470,7 @@ See [`docs/design/README.md`](docs/design/README.md) for the full structure.
 | `platform-ui-generation` | Converting design files into Web/Flutter/WinUI 3 code | generated app code |
 | `milestone-planning` | Planning phases/milestones and the feature breakdown per milestone | `docs/milestones/` phase files |
 | `milestone-execution` | Executing a phase file's milestones one by one with per-milestone steering docs | `.steering/[date]-milestone-NN-[name]/` files |
+| `e2e-testing` | Writing and running Playwright E2E tests as part of every verification step | `e2e/*.spec.ts` + `npm run test:e2e` |
 | `steering` | Planning, implementing, and retrospecting on a task | `.steering/[date]-[name]/` files |
 
 Each skill folder contains a `SKILL.md` (instructions) plus `template.md` and/or `guide.md` (reference