Add Quarkdown render adapter boundary

docs/adapter-boundary.md

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+# Markitect Quarkdown Adapter Boundary
+
+`markitect-quarkdown` provides the concrete `render.quarkdown` adapter for the
+Markitect render/export contract. Core `markitect-tool` owns the passive
+request/result/artifact/provenance contracts; this repository owns Quarkdown
+runtime behavior.
+
+## Adapter Contract
+
+The adapter supports:
+
+- `inspect-profile`
+- `export-source`
+- `render-artifact`
+
+`inspect-profile` and `export-source` do not invoke Quarkdown. `render-artifact`
+requires a Quarkdown CLI plus runtime dependencies.
+
+The adapter descriptor declares filesystem writes, external process execution,
+native renderer dependency, and permission-controlled network behavior. Callers
+can block render execution through Markitect request policy:
+
+```python
+RenderExportRequest(
+    source="# Demo",
+    operation="render-artifact",
+    profile="pdf",
+    policy={"external_process": False},
+)
+```
+
+## Execution Plan
+
+`build_quarkdown_execution_plan` produces an inspectable command plan with:
+
+- Quarkdown command path
+- source file path
+- output directory
+- expected artifact path
+- Markitect profile
+- Quarkdown document type
+- output format
+- permission flags
+- runtime dependency notes
+
+The default output directory is `quarkdown-output`. The default permission
+allow-list is `project-read`, and network access is denied by default.
+
+## Structured Failure
+
+The adapter returns `RenderExportResult` diagnostics instead of raising for
+expected render failures:
+
+- `render.quarkdown.runtime_missing`
+- `render.quarkdown.execution_failed`
+- `render.quarkdown.artifact_missing`
+- `render.quarkdown.artifact_extension`
+- `render.quarkdown.artifact_empty`
+- `render.quarkdown.capability_blocked`
+
+## Artifact Validation
+
+`validate_quarkdown_artifact` validates that the expected artifact exists, has
+the expected extension, is non-empty, and receives a sha256 digest. The result
+is a Markitect `RenderArtifact` with source-to-artifact provenance generated by
+the adapter.

docs/permissions-and-runtime.md

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+# Permissions And Runtime
+
+Quarkdown 2.x introduced compile-time permissions. The Markitect adapter treats
+those as renderer-local execution controls, not as enterprise authorization.
+
+## Permission Mapping
+
+The adapter recognizes Quarkdown permission names as CLI flags:
+
+- `project-read`
+- `global-read`
+- `network`
+- `native-content`
+- `all`
+
+The default allow-list is:
+
+```text
+project-read
+```
+
+The adapter denies `network` by default unless callers explicitly opt out with
+`deny_network: false`.
+
+## Runtime Dependencies
+
+The descriptor declares these optional runtime assumptions:
+
+- Quarkdown 2.x CLI
+- Java 17+
+- Node.js, npm, and Puppeteer for PDF export
+
+The test suite does not require those tools. It uses a fake runner for command
+boundary tests and skips the real-runtime smoke check when `quarkdown` is not
+available on `PATH`.
+
+## Output Conventions
+
+The default output directory is `quarkdown-output`. Expected artifact names are
+derived from `artifact_stem` plus the profile extension, for example
+`demo.pdf` for `profile=pdf`.
+
+This repository owns those conventions and compatibility monitoring. Core
+`markitect-tool` only sees `RenderExportResult`, `RenderArtifact`, diagnostics,
+and provenance.

docs/profile-matrix.md

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+# Quarkdown Profile Matrix
+
+The adapter maps Markitect render profiles onto Quarkdown document/output
+intent. The CLI command is still configurable because Quarkdown distribution
+and command spelling may change across 2.x releases.
+
+| Markitect profile | Quarkdown document type | Output format | Artifact media type | Extension |
+| --- | --- | --- | --- | --- |
+| `plain` | `plain` | `txt` | `text/plain` | `.txt` |
+| `docs` | `docs` | `html` | `text/html` | `.html` |
+| `slides` | `slides` | `html` | `text/html` | `.html` |
+| `paged` | `paged` | `pdf` | `application/pdf` | `.pdf` |
+| `static-site` | `docs` | `html` | `text/html` | `.html` |
+| `pdf` | `paged` | `pdf` | `application/pdf` | `.pdf` |
+
+PDF-oriented profiles require Quarkdown's PDF runtime path, including Java and
+Node.js/npm/Puppeteer assumptions.
+
+## Options
+
+The adapter accepts these stable Markitect-facing options:
+
+- `command`: Quarkdown command name or path, default `quarkdown`
+- `workspace`: temporary working directory override
+- `output_dir`: output directory, default `quarkdown-output`
+- `artifact_stem`: expected artifact basename, default from source stem
+- `permissions`: Quarkdown permission allow-list, default `project-read`
+- `deny_network`: append a network deny flag, default `true`
+- `dry_run`: return an execution-plan artifact without invoking Quarkdown
+
+Renderer packages and automation may add extra options, but they should remain
+under this adapter boundary rather than leaking into `markitect-tool`.