feat(create-sdk): headless creation via --config/--config-json + NDJSON + skill

Add a headless create path: --config <file> / --config-json <json> supply a
structured project spec (answers + feature plan) that drives CreateWizard through
a HeadlessPromptPort, bypassing the TTY. --json emits NDJSON lifecycle events
(done / action-required / error) so an agent can fill a missing input and re-run.
Ship a thin SKILL.md playbook for agent-driven creation. Per-file 100% coverage.

skills/create-dsh-sdk-project/SKILL.md

@@ -0,0 +1,57 @@
+---
+name: create-dsh-sdk-project
+description: Create a DeepSeek Harness SDK project non-interactively (headless), driven by an agent instead of the interactive wizard. Use when asked to scaffold a new DSH SDK project without a terminal.
+---
+
+# Create a DeepSeek Harness SDK project headlessly
+
+The `create-sdk` initializer normally runs an interactive wizard. To create a project
+**without a terminal**, pass a structured spec and ask for machine-readable events:
+
+```sh
+npm create @deepseek-ai/sdk -- --config-json '<spec-json>' --json
+```
+
+- `--config-json '<json>'` supplies the whole spec inline (no prompts). Alternatively
+  `--config <path.json>` reads the same spec from a file.
+- `--json` makes the command emit one NDJSON lifecycle event per line to stdout.
+
+## Spec shape
+
+All fields are optional except those a chosen feature requires. Unsupplied answers that
+have a sensible default are taken from it; a *required* answer with no default (a secret,
+a custom provider base URL, a required feature option) makes the run fail loud rather than
+block.
+
+```json
+{
+  "directory": "my-agent",
+  "description": "A DeepSeek Harness agent",
+  "provider": "deepseek",
+  "apiKey": "<key>",
+  "model": "deepseek-v4-flash",
+  "interface": "stdio",
+  "pm": "npm",
+  "install": false,
+  "features": [
+    { "id": "persistence", "options": ["sqlite"] },
+    { "id": "web", "options": ["exa"], "secrets": { "apiKey": "<exa-key>" } }
+  ]
+}
+```
+
+`features` is the complete set of optional features to enable, each with its chosen
+options and any secrets/values it needs. The interactive feature tree and its
+recommended-feature prompts are skipped in headless mode.
+
+## Reacting to events
+
+Each line of stdout is one JSON object:
+
+- `{"type":"done"}` — the project was created (and installed, if `install` was true).
+- `{"type":"action-required","prompt":"<message>"}` — a required answer was missing.
+  Add the corresponding field to the spec (e.g. an `apiKey`, a feature secret, a custom
+  `baseURL`) and re-run.
+- `{"type":"error","message":"<message>"}` — the run failed for another reason.
+
+Iterate: read `action-required`, fill the named input into the spec, re-run until `done`.