docs: add wiki, .env.example, and fix stale if-curator references

- Add docs/setup.md, docs/troubleshooting.md, docs/faq.md as user-facing wiki
- Add .env.example with all env vars and inline comments
- Fix compose.override.yml: rename service if-curator → winnow, update volume paths
- Fix CHANGELOG.md: rename if-curator → winnow in release notes
- Link docs from README

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

.env.example

@@ -0,0 +1,45 @@
+# ── Required ──────────────────────────────────────────────────────────────────
+IMMICH_URL=http://192.168.1.10:2283
+API_KEY=your-immich-api-key
+FRIGATE_URL=http://192.168.1.10:5000
+
+# ── Mode & Strategy ───────────────────────────────────────────────────────────
+AUTO_MODE=true
+# TRAINING_MODE: face = upload to Frigate face recognition API
+#                object = save crops to output dir for manual Frigate placement
+TRAINING_MODE=face
+# STRATEGY: auto = objective diversity (recommended), standard = 30 imgs, broad = 100 imgs
+STRATEGY=auto
+# LIMIT=50                    # Custom image count; overrides STRATEGY preset
+# OBJECT_CLASS=dog            # Object label for object mode (e.g. dog, cat, car)
+
+# ── People Filtering ──────────────────────────────────────────────────────────
+# ONLY_PEOPLE=John,Jane       # Comma-separated; process only these people
+# SKIP_PEOPLE=Unknown         # Comma-separated; skip these people
+# MIN_FACE_COUNT=5            # Skip people with fewer than N assets in Immich
+# YEARS_FILTER=10             # Only include images from the last N years (default: 10)
+
+# ── Image Quality ─────────────────────────────────────────────────────────────
+# MIN_FACE_WIDTH=50           # Minimum face width in pixels (default: 50)
+# FACE_MARGIN=0.15            # Padding around face crop as fraction (default: 0.15)
+# ENABLE_FACE_ALIGNMENT=true  # Align face before cropping (default: true)
+# USE_FULL_RESOLUTION=true    # Use full-res images vs thumbnails (default: true)
+# MIN_CONFIDENCE=0.7          # Minimum face detection confidence (default: 0.7)
+# BLUR_THRESHOLD=100.0        # Laplacian blur threshold; lower = accept more blur (default: 100.0)
+# MAX_AUTO_IMAGES=80          # Hard cap on auto-diversity selection (default: 80)
+
+# ── Caching & Models ──────────────────────────────────────────────────────────
+FORCE_CPU=false
+ENABLE_CACHE=true
+CACHE_DIR=/app/.if_cache
+HF_HOME=/models/huggingface
+INSIGHTFACE_HOME=/models
+
+# ── Tracker overrides (one-shot — remove after use) ───────────────────────────
+# DRY_RUN=true                # Preview selection without downloading/uploading
+# RETRY_REJECTED=true         # Re-attempt previously rejected images
+# RESET_PERSON=John           # Clear uploaded+rejected history for one person
+
+# ── Scheduling ────────────────────────────────────────────────────────────────
+# Cron expression (unset = run once and exit)
+CRON_SCHEDULE=0 3 * * 0     # Every Sunday at 3 AM