refactor(firmware): remove the retired simulation workflow

Remove the retired simulator workspace member, dependencies, workflow
and documentation. Keep the shared flight and hardware crates.

Validation: retirement prefix host check, command-dispatch tests and
book build.

.github/workflows/sitl-smoke.yml

@@ -1,41 +0,0 @@
-name: Host SITL smoke
-
-on:
-  pull_request:
-  push:
-  workflow_dispatch:
-
-permissions:
-  contents: read
-
-jobs:
-  smoke:
-    name: Deterministic Gazebo command path
-    runs-on: ubuntu-24.04
-    timeout-minutes: 25
-    steps:
-      - name: Check out source
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
-
-      - name: Check host-SITL contracts
-        working-directory: firmware
-        run: |
-          python3 -m unittest tools/sitl/test_kaptan_sim.py
-          python3 tools/sitl/world-structure-test.py
-          cargo check --locked -p kaptan-mavlink --no-default-features
-          cargo check --locked -p kaptan-log --no-default-features
-          cargo check --locked -p kaptan-diagnostics-mavlink
-          cargo test --locked -p kaptan-log
-          cargo test --locked -p kaptan-diagnostics-mavlink
-          if rg -n '(^use log::|\blog::)' platforms/stm32f7/src/f722; then
-            echo 'the standard log facade is forbidden in F722 IRQ/panic paths'
-            exit 1
-          fi
-          if rg -n 'max_level_(off|error|warn|info|debug|trace)' --glob 'Cargo.toml' --glob '*.rs' .; then
-            echo 'log/max_level_* removes records before Kaptan can observe them'
-            exit 1
-          fi
-          cargo test --locked -p kaptan-sitl
-
-      - name: Run Docker closed-loop smoke
-        run: firmware/tools/sitl/e2e-smoke.sh