docs(phase6): documentation site, landing page and open-source scaffolding

Material for MkDocs under docs/, covering self-hosting, the Rune, the
quick-add and filter languages, importing from Todoist, CalDAV,
mail-to-task, MCP, the AI layer and the API. The version is pinned: the
maintainers have announced that MkDocs 2.0 removes the plugin system
with no migration path, and an unpinned install would break this build
on the day it lands.

The landing page shows the quick-add parser as actual text rather than a
screenshot of it — that is the thing worth showing, and it reads better
as the real thing. It shares the app's design tokens, so the site and
what it describes look like one project.

MIT licence, contributing guide, security policy and issue templates.
Pages deployment is behind workflow_dispatch, so the docs build on every
push but nothing is published until the owner chooses to.

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

.github/ISSUE_TEMPLATE/bug.yml

@@ -0,0 +1,43 @@
+name: Bug
+description: Something does not work
+labels: [bug]
+body:
+  - type: textarea
+    id: what
+    attributes:
+      label: What happened
+      description: And what you expected instead.
+    validations:
+      required: true
+  - type: textarea
+    id: steps
+    attributes:
+      label: How to reproduce it
+      placeholder: |
+        1. …
+        2. …
+    validations:
+      required: true
+  - type: input
+    id: version
+    attributes:
+      label: Version
+      description: The image tag, or the commit you built from.
+    validations:
+      required: true
+  - type: dropdown
+    id: how
+    attributes:
+      label: How are you running it
+      options:
+        - As a Rune in Yggdrasil Panel
+        - Docker directly
+        - From source
+    validations:
+      required: true
+  - type: textarea
+    id: logs
+    attributes:
+      label: Anything in the logs
+      description: Please remove tokens and email addresses first.
+      render: text

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Security issue
+    url: https://github.com/kristianwind/verdande/blob/main/SECURITY.md
+    about: Please report vulnerabilities by email, not as a public issue.

.github/ISSUE_TEMPLATE/feature.yml

@@ -0,0 +1,22 @@
+name: Feature
+description: Suggest something
+labels: [enhancement]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Please check the [non-goals](../../blob/main/README.md#non-goals) first —
+        some things are deliberately not being built.
+  - type: textarea
+    id: problem
+    attributes:
+      label: What are you trying to do
+      description: The problem, not the solution. What does the current version make hard?
+    validations:
+      required: true
+  - type: textarea
+    id: idea
+    attributes:
+      label: What you had in mind
+    validations:
+      required: false