feat: slice 2 - all eleven decisions ported to docs/adr

Gate 4, slice 2: decisions/0001-0011 moved via git mv with schema
frontmatter prepended (status and date taken from each body's own
Status line - 0007 stays proposed, its decision is open in #20; bodies
unchanged except relative links gaining one directory level). The old
scheme's README and template retire - their rules already live in
AGENTS.md section 6 and the neckbeard ADR template. Every reference to
decisions/ across the tree retargeted (root files, not-yet-moved
verfahren/hosts/shared files, design doc and session ADR frontmatter).

Verified: validate 0 errors (11 ported + 2 session ADRs + duplicate-id
guard), gen_status --check current with all 13 ADRs listed, drift
check 0 findings, negative test shows a cloned id 0012 firing the
duplicate check.

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

roadmap.md

@@ -39,7 +39,7 @@
 3. Roadmap-/Board-Ausbau in GitLab (Rest von gitops#46: Milestones, Boards).
 4. **Wiki-Oberfläche entscheiden** — [DOC-03 (#20)](https://git.lab/axion1337.chat/management/-/issues/20):
    Docusaurus läuft (`axionwiki.lab`), BookStack steht als Gegenentwurf bereit
-   ([ADR-0007](decisions/0007-wiki-oberflaeche-docusaurus-vs-bookstack.md)). Die Frage
+   ([ADR-0007](docs/adr/0007-wiki-oberflaeche-docusaurus-vs-bookstack.md)). Die Frage
    dahinter: Doku im Repo oder im Browser? Verfallsdatum Ende August.
 5. Sicherheits-Nachlese aus der VPN-Nacht:
    [CFGMON-14 (#14)](https://git.lab/axion1337.chat/management/-/issues/14) docker-Gruppe