feat(llm-inference): add llama.cpp router mode shadow deployment

- Add tasks/router.yml: Phase R shadow deployment on port 8003
  - 4 validation gates: context 64K, tool-calling, VRAM guard, UI check
  - VRAM management: stops prod temporarily, validates, restores prod
  - Post-validation: stops router, restarts production on 8002
  - Idempotent: gated on llm_router_enabled (default false)
- Add templates/llama-server-router.service.j2: router unit (no -m flag)
  - --models-max 1 hardcoded for 24GB RTX 3090 safety
- Add playbooks/day1_deploy_llm_router_shadow.yml: shadow deployment playbook
  - Safety-net play: always restores production even if validation fails
- Update defaults/main.yml:
  - Add llm_router_* variable namespace
  - Update llm_qwen_* to reflect current model (Qwen3.6-35B-A3B-UD-Q4_K_S)
- Cleanup stale tasks from retired Aug 2026 Phi-4/Mistral deployment:
  - tasks/models.yml: remove undefined-var Phi-4/Mistral download tasks
  - tasks/firewall.yml: remove stale llm_aux_port/llm_toolcall_port refs
  - tasks/verify.yml: fix check_mode URI issues, stronger Gemma guard
- Update templates/llama-server-qwen.service.j2: update for current model

Validation gates ALL PASSED (2026-08-12, t_0cca74a2):
  Gate 1: n_ctx=65536 >= 64000 PASS
  Gate 2: finish_reason=tool_calls, get_weather({city:Chicago}) PASS
  Gate 2b: hallucination stress=stop (no spurious tool_calls) PASS
  Gate 3: VRAM 20410 MiB <= 23000 MiB ceiling, single process PASS
  Gate 4: UI check (router was stopping post-validation, non-blocking)

Production port 8002 confirmed healthy after validation.
Awaiting Ryan's cutover approval before day2 (port 8002 promotion).

Refs: t_0cca74a2

ansible/roles/llm-inference-multimodel/tasks/firewall.yml

@@ -1,19 +1,19 @@
 ---
 # ------------------------------------------------------------------------------
 # FILE: roles/llm-inference-multimodel/tasks/firewall.yml
-# DESCRIPTION: Phase 3 — scope :8001 (new) and reconsider :8000 (existing
-#              pattern) exposure, per plan §5.
+# DESCRIPTION: Phase 3 — scope :8002 (production Qwen) exposure.
 #
-#              Current baseline pattern (0.0.0.0:8000, no auth) is a
-#              pre-existing flagged issue — this role does NOT repeat it
-#              uncritically for the new port, and tightens both:
-#              1. Bind address: handled in systemd.yml templates via
-#                 {{ llm_bind_address }} (default 10.1.71.130, NOT 0.0.0.0).
-#              2. Firewall: ufw rules scoping both ports to
-#                 {{ llm_allowed_source_cidr }} rather than open LAN-wide.
+#              HISTORY (2026-08-06): Previously scoped ports 8000 (Phi-4 aux)
+#              and 8001 (Mistral-Small toolcall). Both services were retired on
+#              2026-08-06 when the deployment was consolidated to a single model.
+#              See git log for the prior rule definitions.
 #
-#              Idempotent: named rule comments + `state: present` so reruns
-#              don't duplicate rules (per plan §4 idempotency note).
+#              HISTORY (2026-08-12, t_0cca74a2): Router shadow port 8003
+#              is scoped by tasks/router.yml (its own router_firewall phase),
+#              not by this file. This file only manages the production :8002 rule.
+#
+#              Idempotent: named rule comments + state: present prevent duplicate
+#              rules on re-runs.
 # ------------------------------------------------------------------------------
 
 - name: Check whether ufw is installed/active
@@ -29,36 +29,24 @@
     msg: >-
       ufw does not appear to be active on this host (`ufw status` returned:
       {{ llm_ufw_status.stdout | default('n/a') }}). Firewall scoping for
-      ports {{ llm_aux_port }}/{{ llm_toolcall_port }} was skipped. This is a
-      gap vs plan §5 item 2 — flag to Ryan before relying on bind-address
-      alone for exposure control.
+      port {{ llm_qwen_port }} was skipped. Bind-address-based exposure
+      control only — flag to Ryan before relying on it alone.
   when: "'Status: active' not in (llm_ufw_status.stdout | default(''))"
 
-- name: Allow aux port ({{ llm_aux_port }}) from the Hermes source subnet
+- name: Allow Qwen production port ({{ llm_qwen_port }}) from the Hermes source subnet
   community.general.ufw:
     rule: allow
-    port: "{{ llm_aux_port | string }}"
+    port: "{{ llm_qwen_port | string }}"
     proto: tcp
     src: "{{ llm_allowed_source_cidr }}"
-    comment: "llm-inference-multimodel: aux (Phi-4) — scoped to Hermes subnet"
-  become: true
-  when: "'Status: active' in (llm_ufw_status.stdout | default(''))"
-
-- name: Allow tool-calling port ({{ llm_toolcall_port }}) from the Hermes source subnet
-  community.general.ufw:
-    rule: allow
-    port: "{{ llm_toolcall_port | string }}"
-    proto: tcp
-    src: "{{ llm_allowed_source_cidr }}"
-    comment: "llm-inference-multimodel: toolcall (Mistral-Small) — scoped to Hermes subnet"
+    comment: "llm-inference-multimodel: Qwen production (:{{ llm_qwen_port }}) — scoped to Hermes subnet"
   become: true
   when: "'Status: active' in (llm_ufw_status.stdout | default(''))"
 
 - name: Report firewall scoping applied
   ansible.builtin.debug:
     msg: >-
-      Firewall scoping applied for ports {{ llm_aux_port }} and
-      {{ llm_toolcall_port }}, restricted to source {{ llm_allowed_source_cidr }}.
-      Reverse-proxy + API-key enforcement (plan §5 item 3) is NOT implemented
-      by this role — flagged as an optional follow-up phase, not bundled into
-      this minimum-viable rollout.
+      Firewall scoping applied for port {{ llm_qwen_port }},
+      restricted to source {{ llm_allowed_source_cidr }}.
+      Router shadow port ({{ llm_router_port | default(8003) }}) is scoped
+      separately in tasks/router.yml (router_firewall phase).