cleanup: remove stale .mindmodel, old venvs, orphaned code, and transient artifacts

Removes:
- .mindmodel/ directory and related CI workflows (mindmodel-schedule.yml, mindmodel-validation.yml)
- scripts/mindmodel/ and scripts/validate_mindmodel.py
- src/types/ and src/validators/ (orphaned type modules, only used by mindmodel)
- tests/ci/, tests/scripts/mindmodel/, tests/types/, tests/validators/ (mindmodel-only tests)
- thoughts/ledgers/ and thoughts/shared/ (stale transient directories)
- .venv_axis and .venv_plotly (orphaned virtual environments, ~1.1 GB)
- outputs/blog-charts/ (stale generated HTML files)
- data/*.json sidecars (empty cache artifacts)
- __pycache__ and *.pyc files across repo

Updates:
- .gitignore: remove thoughts/shared/analyses/ entry

Space reclaimed: ~1.1 GB+

.github/workflows/mindmodel-schedule.yml

@@ -1,37 +0,0 @@
-name: mindmodel scheduled validate
-
-on:
-  schedule:
-    - cron: '0 0 * * 0' # weekly
-
-jobs:
-  validate:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-
-      - name: Install uv
-        uses: astral-sh/setup-uv@v5
-        with:
-          version: "0.6.x"
-
-      - name: Set up Python
-        uses: actions/setup-python@v5
-        with:
-          python-version: "3.13"
-
-      - name: Install dependencies
-        run: uv sync --locked
-
-      - name: Run tests
-        run: uv run pytest tests/ -q
-
-      - name: Run mindmodel validator if manifest exists
-        if: ${{ always() }}
-        run: |
-          if [ -f .mindmodel/manifest.yaml ]; then
-            uv run python -m scripts.mindmodel.cli || true
-          else
-            echo "No .mindmodel/manifest.yaml present — skipping validator"
-          fi

.github/workflows/mindmodel-validation.yml

@@ -1,47 +0,0 @@
-name: mindmodel validation
-
-on:
-  push:
-    branches: [ main ]
-  pull_request:
-    branches: [ main ]
-
-jobs:
-  validate:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-
-      - name: Set up Python
-        uses: actions/setup-python@v4
-        with:
-          python-version: '3.x'
-
-      - name: Install development dependencies (if present)
-        run: |
-          python -m pip install --upgrade pip
-          if [ -f requirements-dev.txt ]; then
-            pip install -r requirements-dev.txt
-          else
-            echo "requirements-dev.txt not found, skipping"
-          fi
-
-      - name: Run mindmodel validator (report-only)
-        if: ${{ always() }}
-        run: |
-          # Make this step report-only: run the validator but always exit 0 so PRs are not blocked
-          set +e
-          if [ -f .mindmodel/manifest.yaml ]; then
-            python scripts/validate_mindmodel.py --manifest .mindmodel/manifest.yaml --report reports/out.json || true
-          else
-            echo "No .mindmodel/manifest.yaml present — skipping validator"
-          fi
-          exit 0
-
-      - name: Upload mindmodel reports
-        if: ${{ always() }}
-        uses: actions/upload-artifact@v4
-        with:
-          name: mindmodel-reports
-          path: reports/mindmodel-report-*.json