Complete rewrite: SnapRAID SMART logger with BackBlaze algorithm

Fetches SMART data from Scrutiny's InfluxDB and calculates failure
probabilities using the exact BackBlaze tables from SnapRAID source.

Key features:
- Calculates both v12 (with attr 193) and v13 (without attr 193) algorithms
- v12 matches SnapRAID pre-v13.0 (includes Load Cycle Count)
- v13 matches modern SnapRAID v13.0+ (excludes Load Cycle Count)
- Stores both values for trending and comparison
- Correctly applies bit masks (16-bit for 187/188, 32-bit for others)
- Annualizes monthly rates and applies Poisson distribution
- Logs to PostgreSQL with device metadata

Solved the mystery: SnapRAID v12 uses attribute 193 which was removed
in v13.0. Load cycle count has massive impact on failure predictions
for some drives (80% vs 4% difference).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

schema.sql

@@ -0,0 +1,58 @@
+-- PostgreSQL schema for SMART data logging
+
+-- Main table for SMART metrics snapshots
+CREATE TABLE IF NOT EXISTS smart_metrics (
+    id BIGSERIAL PRIMARY KEY,
+    timestamp TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    device_path VARCHAR(255) NOT NULL,
+    serial_number VARCHAR(255) NOT NULL,
+    model VARCHAR(255),
+    disk_role VARCHAR(50),  -- e.g., 'd1', 'd2', 'parity', '2-parity', or '-' for unused
+
+    -- Basic metrics (from SnapRAID smart output)
+    temperature_celsius INTEGER,
+    power_on_days INTEGER,
+    error_count INTEGER,
+    size_tb DECIMAL(10, 2),
+
+    -- Calculated failure probability
+    failure_probability_pct DECIMAL(5, 2),  -- 0.00 to 100.00
+
+    -- Raw SMART attributes (key-value pairs as JSONB)
+    smart_attributes JSONB,
+
+    -- Indexes for efficient querying
+    CONSTRAINT unique_device_timestamp UNIQUE (device_path, timestamp)
+);
+
+-- Index on serial number for device history queries
+CREATE INDEX IF NOT EXISTS idx_smart_metrics_serial ON smart_metrics(serial_number);
+
+-- Index on timestamp for time-range queries
+CREATE INDEX IF NOT EXISTS idx_smart_metrics_timestamp ON smart_metrics(timestamp DESC);
+
+-- Index on device_path for per-device queries
+CREATE INDEX IF NOT EXISTS idx_smart_metrics_device ON smart_metrics(device_path);
+
+-- Index on JSONB attributes for querying specific SMART values
+CREATE INDEX IF NOT EXISTS idx_smart_attributes_gin ON smart_metrics USING gin (smart_attributes);
+
+-- View for latest metrics per device
+CREATE OR REPLACE VIEW smart_latest AS
+SELECT DISTINCT ON (device_path)
+    *
+FROM smart_metrics
+ORDER BY device_path, timestamp DESC;
+
+-- View for high-risk devices (failure probability > 50%)
+CREATE OR REPLACE VIEW smart_high_risk AS
+SELECT *
+FROM smart_latest
+WHERE failure_probability_pct > 50.0
+ORDER BY failure_probability_pct DESC;
+
+COMMENT ON TABLE smart_metrics IS 'Historical SMART metrics collected from Scrutiny InfluxDB';
+COMMENT ON COLUMN smart_metrics.failure_probability_pct IS 'BackBlaze-based 1-year failure probability (0-100%)';
+COMMENT ON COLUMN smart_metrics.smart_attributes IS 'Raw SMART attributes as JSON (attribute_id -> value)';
+COMMENT ON VIEW smart_latest IS 'Latest SMART metrics for each device';
+COMMENT ON VIEW smart_high_risk IS 'Devices with >50% annual failure probability';