feat(semaphore): add config-as-code via Semaphore REST API

Adds an idempotent configuration pass that drives a freshly-deployed
Semaphore instance into its desired state via the REST API. Declared
in group_vars/all/semaphore.yml, applied by tasks/configure.yml,
toggled by semaphore_configure feature flag (default off).

Object types managed:
  - Project (mk-labs)
  - Keys (ansible-vault-pass, gitea-deploy, jarvis-ssh)
  - Repositories (homelab on gitea)
  - Inventories (production -> ansible/inventory.yml in homelab repo)
  - Environments (default with ANSIBLE_HOST_KEY_CHECKING=False)
  - Templates (day0_linux_baseline + variants, day1_deploy_semaphore)
    with survey vars for runtime parameters

Each object found-or-created by name; existing ones never modified.
no_log on token-bearing calls to keep secrets out of stdout.

Inputs (already in vault):
  vault_semaphore_api_token
  vault_jarvis_ssh_private_key
  vault_gitea_deploy_key
  vault_ansible_vault_password

ansible/group_vars/all/semaphore.yml

@@ -0,0 +1,132 @@
+---
+# ============================================================================
+# Semaphore configuration-as-code
+# ============================================================================
+# Drives a freshly-deployed Semaphore instance into its desired state via
+# the Semaphore REST API. Idempotent: every object is checked first; only
+# missing ones are created. Existing objects are left alone.
+#
+# Loaded from group_vars/all/semaphore.yml so that the configuration is
+# version-controlled in the homelab repo and survives a wipe-and-redeploy
+# of the Semaphore VM.
+# ============================================================================
+
+# ---------------------------------------------------------------------------
+# API connection (defaults to the local Traefik-fronted service-name URL).
+# Override semaphore_api_url to point at a specific instance if needed.
+# ---------------------------------------------------------------------------
+semaphore_api_url: "https://semaphore.local.mk-labs.cloud/api"
+semaphore_api_validate_certs: true
+semaphore_api_token: "{{ vault_semaphore_api_token }}"
+
+# Feature flag — keeps day1_deploy_semaphore.yml deploy-only by default.
+# Set true to also run the configuration pass.
+semaphore_configure: false
+
+# ---------------------------------------------------------------------------
+# Declarative configuration of the Semaphore instance.
+# ---------------------------------------------------------------------------
+#
+# Top-level shape:
+#
+#   semaphore_config:
+#     project:        single dict — the lab uses one project ("mk-labs")
+#     keys:           list of credentials Semaphore stores
+#     repositories:   git repos Semaphore can clone
+#     inventories:    Ansible inventories from those repos
+#     environments:   env-var bundles
+#     templates:      task templates that tie everything together
+#
+# Each list element has a unique "name" used as the natural identity key.
+# ---------------------------------------------------------------------------
+
+semaphore_config:
+  project:
+    name: mk-labs
+    alert: false
+    max_parallel_tasks: 0  # 0 = unlimited
+
+  keys:
+    # The ansible-vault password. login_password type with empty login
+    # — only the password field is consumed by Semaphore at runtime.
+    - name: ansible-vault-pass
+      type: login_password
+      login: ""
+      password: "{{ vault_ansible_vault_password }}"
+
+    # SSH key for the gitea deploy access (clone the homelab repo).
+    - name: gitea-deploy
+      type: ssh
+      ssh_login: git
+      ssh_private_key: "{{ vault_gitea_deploy_key }}"
+
+    # SSH key Semaphore uses to reach the fleet as jarvis.
+    - name: jarvis-ssh
+      type: ssh
+      ssh_login: jarvis
+      ssh_private_key: "{{ vault_jarvis_ssh_private_key }}"
+
+  repositories:
+    - name: homelab
+      git_url: "ssh://git@gitea.mk-labs.cloud:2221/rblundon/homelab.git"
+      git_branch: main
+      ssh_key: gitea-deploy
+
+  inventories:
+    - name: production
+      type: file
+      inventory_file: ansible/inventory.yml
+      repository: homelab
+      ssh_key: jarvis-ssh
+      become_key: jarvis-ssh
+
+  environments:
+    - name: default
+      env:
+        ANSIBLE_HOST_KEY_CHECKING: "False"
+        ANSIBLE_FORCE_COLOR: "True"
+
+  templates:
+    - name: "day0_linux_baseline"
+      description: "Apply the mk-labs Linux baseline to one or more hosts."
+      app: ansible
+      playbook: ansible/playbooks/day0_linux_baseline.yml
+      inventory: production
+      repository: homelab
+      environment: default
+      vault_password: ansible-vault-pass
+      arguments: '["--diff"]'
+      survey_vars:
+        - name: target
+          title: "Target host or group"
+          description: "Inventory target (e.g. figment, semaphore_server, all)"
+          required: true
+          type: TextVar
+          default_value: "all"
+
+    - name: "day1_deploy_semaphore"
+      description: "Re-deploy Semaphore + PostgreSQL on figment."
+      app: ansible
+      playbook: ansible/playbooks/day1_deploy_semaphore.yml
+      inventory: production
+      repository: homelab
+      environment: default
+      vault_password: ansible-vault-pass
+      arguments: '["--diff"]'
+
+    - name: "day0_linux_baseline_check"
+      description: "Dry-run the baseline — shows diffs, applies nothing."
+      app: ansible
+      playbook: ansible/playbooks/day0_linux_baseline.yml
+      inventory: production
+      repository: homelab
+      environment: default
+      vault_password: ansible-vault-pass
+      arguments: '["--check","--diff"]'
+      survey_vars:
+        - name: target
+          title: "Target host or group"
+          description: "Inventory target (e.g. figment, semaphore_server, all)"
+          required: true
+          type: TextVar
+          default_value: "all"