feat(registry): add playwright capability group (6 TS browser fns)

New domain `browser` under frontend/functions/ with 6 Playwright helpers:
- pw_launch_browser: chromium + context + page bootstrap with storageState
  support and baseUrl navigation.
- pw_kanban_login: authenticates a Page against /api/auth/login; sets the
  kanban_session cookie via shared storageState; verifies login page no
  longer visible after navigation.
- pw_drag_drop: human-like pointer drag (mousedown + activateOffset +
  stepped move + mouseup) compatible with @dnd-kit/core's 8px activation
  threshold; supports hoverMs for time-based dropzones.
- pw_keyboard_sequence: ordered focus/type/press/wait steps for scripting
  realistic input flows (typing then arrow-key navigating autocompletes).
- pw_wait_predicate: thin wrapper over page.waitForFunction with friendlier
  defaults and custom error messages.
- pw_assert_class: poll-based assertion that a Locator has/lacks a CSS
  class within a timeout; useful for visual-state checks.

Each function ships with vitest tests (5-8 cases each) covering both happy
and error paths, plus self-documenting .md (Ejemplo + Cuando usarla +
Gotchas + frontmatter with params/output schema).

Adds frontend/functions/package.json with `"type": "module"` so consumers
can ESM-import the .ts files from anywhere in the registry (Playwright's
tsx loader respects nearest package.json).

Capability page docs/capabilities/playwright.md documents the group with
a canonical end-to-end example, frontiers, prerequisites, and gotchas.
Index updated.

First consumer (issue 0088): apps/kanban requester-input.spec.ts.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/functions/browser/pw_keyboard_sequence.md

@@ -0,0 +1,59 @@
+---
+name: pw_keyboard_sequence
+kind: function
+lang: ts
+domain: browser
+version: "1.0.0"
+purity: impure
+signature: "async (page: Page, sequence: KbStep[]) => Promise<void>"
+description: "Executes a sequence of keyboard interactions (focus, type, key press, wait) on a Playwright Page. Use to script realistic input flows like typing then navigating autocomplete dropdowns with arrow keys."
+tags: ["playwright", "e2e", "browser", "keyboard"]
+params:
+  - name: page
+    desc: "Playwright Page."
+  - name: sequence
+    desc: "Array of steps: focus/type/press/wait. Executed in order."
+output: "void; mutates focused element / page state."
+uses_functions: []
+uses_types: []
+returns: []
+returns_optional: false
+error_type: "error_go_core"
+imports: ["playwright"]
+tested: true
+tests:
+  - "focus calls focus"
+  - "type uses default delay"
+  - "press routes correctly"
+  - "wait calls waitForTimeout"
+  - "unknown kind throws"
+  - "order preserved"
+test_file_path: "frontend/functions/browser/pw_keyboard_sequence.test.ts"
+file_path: "frontend/functions/browser/pw_keyboard_sequence.ts"
+---
+
+## Ejemplo
+
+```ts
+import { pw_keyboard_sequence } from "./pw_keyboard_sequence";
+
+await pw_keyboard_sequence(page, [
+  { kind: "focus", selector: "input[name=requester]" },
+  { kind: "type", text: "Enma" },
+  { kind: "wait", ms: 200 },
+  { kind: "press", key: "ArrowDown" },
+  { kind: "press", key: "ArrowDown" },
+  { kind: "press", key: "Enter" },
+]);
+```
+
+## Cuando usarla
+
+Cuando necesites encadenar foco + escritura + teclas especiales sobre un elemento (autocompletado, selects, modales de búsqueda). Úsala en tests E2E con Playwright en lugar de mezclar calls sueltas de `keyboard.type` y `keyboard.press`.
+
+## Gotchas
+
+- `focus` usa `.first()` — si el selector coincide con múltiples elementos, foca el primero. Afinar el selector si es necesario.
+- `type` simula escritura carácter a carácter con `delay` (default 30 ms). Para input más rápido pasar `delayMs: 0`.
+- `press` espera un nombre de tecla Playwright válido: `"ArrowDown"`, `"Enter"`, `"Escape"`, `"Tab"`, etc.
+- Un `kind` desconocido lanza en runtime (útil para detectar typos en JS sin TypeScript).