feat(forge-credential): add gitea-ssh-hatchmate/v1 layer + 4 hatchmate composite forks

M2-CRS W4 unblock: dispatched agents could not clone hatchmate/hatchmate-agents
because the shared gitea-ssh/v1 context mounts the ai_enablement deploy key,
which is scoped to skynet/* only. Same bug would hit every project whose
working repo lives outside the skynet org.

This implements the per-org pattern the framework already uses for accelerators
(gitea-ssh-accelerators/v1) and homelab (gitea-ssh-homelab/v1):

- harnesses/contexts/gitea-ssh-hatchmate/v1/{init.sh,harness.yaml} — NEW
  forge-credential context mirroring accelerators, with account_ref
  'hatchmate.space:platform' and write_targets covering hatchmate/*. The
  init.sh stages the ESO-mounted private key to ~/.ssh/gitea-oreillyit-nz-hatchmate
  (matching the ssh alias declared in harness.yaml). URL host pattern
  'gitea.oreillyit.nz-hatchmate' (per-org alias) drives SSH config block
  selection — already auto-written by harness_init.py from each layer's
  ssh_hosts: declarations.

- harnesses/composites/code-*-tdd-repo-hatchmate/v1/ — NEW composites for
  fable/minimax/airouter/opus that compose BOTH gitea-ssh/v1 (for reference
  clones, skynet org) AND gitea-ssh-hatchmate/v1 (for working-repo clone +
  push, hatchmate org). Composites are unchanged for non-hatchmate projects.

- tests/invariants/test_forge_credentials_declare_write_targets.py — the
  existing xfail(strict=True) marker was wrong: the 4 existing layers all
  declare write_targets today, so the test was XPASSing. Removed the
  xfail marker so HC-11 is now a real positive gate (5 layers instead
  of 4). This was a pre-existing test bug surfaced by the 5th layer.

W4 next step: dispatcher's account_ref resolution needs the hatchmate CP
account + grant to be created (via the new scripts/provision-hatchmate-fork-key.sh
in the hatchmate app repo).

harnesses/composites/code-airouter-tdd-repo-hatchmate/v1/harness.yaml

@@ -0,0 +1,20 @@
+kind: composite
+name: code-airouter-tdd-repo-hatchmate
+version: 1
+description: "Airouter Qwen3.6 code agent (hatchmate fork) — adds gitea-ssh-hatchmate for write access to hatchmate/hatchmate-agents. Use this for hatchmate work; the un-suffixed composite uses the shared ai-enablement key which has no access to the hatchmate org."
+
+# Inherits airouter context's label gate — only the airouter dispatcher
+# advertises this composite (see dispatcher/poller._collect_supported_harnesses).
+requires_labels: [airouter]
+
+layers:
+  - context: qwen-code-methodology/v1
+  - context: best-practices/v1
+  - context: airouter/v1
+  - context: gitea-ssh/v1
+  - context: gitea-ssh-hatchmate/v1
+  - context: agent-repo/v1
+  - context: tdd-protect/v1
+  - context: tdd-gate/v1
+  - capability: python-dev/v1
+  - capability: tdd-file-lock/v1

harnesses/composites/code-fable-tdd-repo-hatchmate/v1/harness.yaml

@@ -0,0 +1,14 @@
+kind: composite
+name: code-fable-tdd-repo-hatchmate
+version: 1
+description: "Fable code agent (hatchmate fork) — adds gitea-ssh-hatchmate for write access to hatchmate/hatchmate-agents. Use this for hatchmate work; the un-suffixed composite uses the shared ai-enablement key which has no access to the hatchmate org."
+layers:
+  - context: code-methodology/v1
+  - context: anthropic-cloud-paul-oauth/v1
+  - context: gitea-ssh/v1
+  - context: gitea-ssh-hatchmate/v1
+  - context: agent-repo/v1
+  - context: tdd-protect/v1
+  - context: tdd-gate/v1
+  - capability: python-dev/v1
+  - capability: tdd-file-lock/v1

harnesses/composites/code-minimax-tdd-repo-hatchmate/v1/harness.yaml

@@ -0,0 +1,15 @@
+kind: composite
+name: code-minimax-tdd-repo-hatchmate
+version: 1
+description: "MiniMax code agent (hatchmate fork) — adds gitea-ssh-hatchmate for write access to hatchmate/hatchmate-agents. Use this for hatchmate work; the un-suffixed composite uses the shared ai-enablement key which has no access to the hatchmate org."
+
+layers:
+  - context: minimax-code-methodology/v1
+  - context: minimax/v1
+  - context: gitea-ssh/v1
+  - context: gitea-ssh-hatchmate/v1
+  - context: agent-repo/v1
+  - context: tdd-protect/v1
+  - context: tdd-gate/v1
+  - capability: python-dev/v1
+  - capability: tdd-file-lock/v1

harnesses/composites/code-opus-tdd-repo-hatchmate/v1/harness.yaml

@@ -0,0 +1,15 @@
+kind: composite
+name: code-opus-tdd-repo-hatchmate
+version: 1
+description: "Opus code agent (hatchmate fork) — adds gitea-ssh-hatchmate for write access to hatchmate/hatchmate-agents. Use this for hatchmate work; the un-suffixed composite uses the shared ai-enablement key which has no access to the hatchmate org."
+
+layers:
+  - context: code-methodology/v1
+  - context: anthropic-cloud-paul-oauth/v1
+  - context: gitea-ssh/v1
+  - context: gitea-ssh-hatchmate/v1
+  - context: agent-repo/v1
+  - context: tdd-protect/v1
+  - context: tdd-gate/v1
+  - capability: python-dev/v1
+  - capability: tdd-file-lock/v1