feat: copier update v0.9.0 — extraction docs, state tracking, architecture guides

Sync template from 29ac25b → v0.9.0 (29 template commits). Due to
template's _subdirectory migration, new files were manually rendered
rather than auto-merged by copier.

New files:
- .claude/CLAUDE.md + coding_philosophy.md (agent instructions)
- extract utils.py: SQLite state tracking for extraction runs
- extract/transform READMEs: architecture & pattern documentation
- infra/supervisor: systemd service + orchestration script
- Per-layer model READMEs (raw, staging, foundation, serving)

Also fixes copier-answers.yml (adds 4 feature toggles, removes stale
payment_provider key) and scopes CLAUDE.md gitignore to root only.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

extract/padelnomics_extract/README.md

@@ -0,0 +1,90 @@
+# Padelnomics Extraction
+
+Fetches raw data from external sources to the local landing zone. The pipeline then reads from the landing zone — extraction and transformation are fully decoupled.
+
+## Running
+
+```bash
+# One-shot (most recent data only)
+LANDING_DIR=data/landing uv run extract
+
+# First-time full backfill (add your own backfill entry point)
+LANDING_DIR=data/landing uv run python -m padelnomics_extract.execute
+```
+
+## Design: filesystem as state
+
+The landing zone is an append-only store of raw files. Each file is named by its content fingerprint (etag or SHA256 hash), so:
+
+- **Idempotency**: running twice writes nothing if the source hasn't changed
+- **Debugging**: every historical raw file is preserved — reprocess any window by re-running transforms
+- **Safety**: extraction never mutates existing files, only appends new ones
+
+### Etag-based dedup (preferred)
+
+When the source provides an `ETag` header, use it as the filename:
+
+```
+data/landing/padelnomics/{year}/{month:02d}/{etag}.csv.gz
+```
+
+The file existing on disk means the content matches the server's current version. No content download needed.
+
+### Hash-based dedup (fallback)
+
+When the source has no etag (static files that update in-place), download the content and use its SHA256 prefix as the filename:
+
+```
+data/landing/padelnomics/{year}/{date}_{sha256[:8]}.csv.gz
+```
+
+Two runs that produce identical content produce the same hash → same filename → skip.
+
+## State tracking
+
+Every run writes one row to `data/landing/.state.sqlite`. Query it to answer operational questions:
+
+```bash
+# When did extraction last succeed?
+sqlite3 data/landing/.state.sqlite \
+  "SELECT extractor, started_at, status, files_written, files_skipped, cursor_value
+   FROM extraction_runs ORDER BY run_id DESC LIMIT 10"
+
+# Did anything fail in the last 7 days?
+sqlite3 data/landing/.state.sqlite \
+  "SELECT * FROM extraction_runs WHERE status = 'failed'
+   AND started_at > datetime('now', '-7 days')"
+```
+
+State table schema:
+
+| Column | Type | Description |
+|--------|------|-------------|
+| `run_id` | INTEGER | Auto-increment primary key |
+| `extractor` | TEXT | Extractor name (e.g. `padelnomics`) |
+| `started_at` | TEXT | ISO 8601 UTC timestamp |
+| `finished_at` | TEXT | ISO 8601 UTC timestamp, NULL if still running |
+| `status` | TEXT | `running` → `success` or `failed` |
+| `files_written` | INTEGER | New files written this run |
+| `files_skipped` | INTEGER | Files already present (content unchanged) |
+| `bytes_written` | INTEGER | Compressed bytes written |
+| `cursor_value` | TEXT | Last successful cursor (date, etag, page, etc.) |
+| `error_message` | TEXT | Exception message if status = `failed` |
+
+## Adding a new extractor
+
+1. Add a function in `execute.py` following the same pattern as `extract_file_by_etag()` or `extract_file_by_hash()`
+2. Call it from `extract_dataset()` with its own `extractor` name in `start_run()`
+3. Store files under a new subdirectory: `landing_path(LANDING_DIR, "my_new_source", year)`
+4. Add a new SQLMesh `raw/` model that reads from the new subdirectory glob
+
+## Landing zone structure
+
+```
+data/landing/
+├── .state.sqlite              # extraction run history
+└── padelnomics/               # one subdirectory per source
+    └── {year}/
+        └── {month:02d}/
+            └── {etag}.csv.gz  # immutable, content-addressed files
+```