refactor(log): replace stdlib log with the application JSON logger

Every log.Printf/Fatalf becomes a structured slog call through
internal/log: request handlers use the request-scoped logger
(applog.FromContext, carrying request_id), startup failures exit via a
fatal() helper that still emits JSON, and the seedsample/dumpschema CLIs
bootstrap the same JSON logger. Stale client_test expectations aligned
with the refactored wrapper-call logging (message casing, result attr,
ERROR level).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/internal/store/profiles.go

@@ -0,0 +1,148 @@
+package store
+
+import (
+	"context"
+	"fmt"
+)
+
+// Profile is the single active user's Garmin credentials plus every
+// tunable analysis-engine parameter. Always exactly one row (id=1).
+type Profile struct {
+	GarminEmail    string
+	GarminPassword string
+	// GarminConnectedAt is nil until this user's first successful Garmin
+	// authentication (see store.MarkGarminConnected) -- the login gate uses
+	// it, not UpdateProfile, so it's deliberately excluded from
+	// UpdateProfile's SET clause below and can only ever move from nil to
+	// set, never reset by a normal profile save.
+	GarminConnectedAt *string
+	RollingWindowDays int
+	// BackfillHorizonDays bounds how far back "Sync now" reaches when
+	// walking backward from today; it's read fresh on every sync (not fixed
+	// at server startup), so changing it here takes effect on the next
+	// click. Unrelated to RollingWindowDays, which is for the (not yet
+	// implemented) relative classification window.
+	BackfillHorizonDays int
+	MaxHeartRate        *float64
+	RestingHeartRate    *float64
+
+	HRZone1MinPct, HRZone1MaxPct float64
+	HRZone2MinPct, HRZone2MaxPct float64
+	HRZone3MinPct, HRZone3MaxPct float64
+	HRZone4MinPct, HRZone4MaxPct float64
+	HRZone5MinPct, HRZone5MaxPct float64
+
+	// WarmupMinutes/CooldownMinutes apply uniformly to every fixed-duration
+	// workout type's phase detection (Easy, Long, Tempo, Threshold 30'/60',
+	// MAS Test). Interval workouts detect phases from lap data directly and
+	// don't use these.
+	WarmupMinutes, CooldownMinutes float64
+
+	// MinRepresentativePaceSecPerKm/MinRepresentativeTimeSeconds drive the
+	// Review Queue pace chart's artifact filter: a stretch of samples slower
+	// than MinRepresentativePaceSecPerKm is dropped from the chart (and its
+	// Y-axis scale) unless it persists for at least
+	// MinRepresentativeTimeSeconds, in which case it's treated as a real
+	// stop or walk break rather than noise (e.g. GPS/motion still settling
+	// right as recording starts, before the run itself begins).
+	MinRepresentativePaceSecPerKm, MinRepresentativeTimeSeconds float64
+
+	// Chart colors: PaceColor/HeartRateColor are the "main line" color for
+	// each metric's chart; Warmup/Effort/Recovery/CooldownColor are the
+	// "effort kind" colors. The frontend derives the under-the-line fill
+	// (effort color tinted by the main line color) and the phase background
+	// fill (effort color, darkened) from these six -- see
+	// frontend's ExpectedVsActualChart.
+	PaceColor, HeartRateColor                              string
+	WarmupColor, EffortColor, RecoveryColor, CooldownColor string
+	// MainLineTintPct (0-100) is how strongly the main line color mixes into
+	// the effort-kind fill under the line -- see frontend's mixColor(). Never
+	// affects the phase background above the line.
+	MainLineTintPct float64
+	// BackgroundDarkenPct (0-100) is how strongly the effort-kind color is
+	// darkened for the phase background above the line -- see frontend's
+	// darken(). Never mixed with the main line color.
+	BackgroundDarkenPct float64
+	// TargetBrightenPct (0-100) is how strongly a chart's main line color
+	// (and everything tinted from it) is brightened when that chart has a
+	// structured-workout target range to show -- a color cue for "this has a
+	// target" instead of a text label -- see frontend's brighten().
+	TargetBrightenPct float64
+
+	CreatedAt, UpdatedAt string
+}
+
+const profileColumns = `
+	garmin_email, garmin_password, garmin_connected_at, rolling_window_days, backfill_horizon_days, max_heart_rate, resting_heart_rate,
+	hr_zone1_min_pct, hr_zone1_max_pct, hr_zone2_min_pct, hr_zone2_max_pct,
+	hr_zone3_min_pct, hr_zone3_max_pct, hr_zone4_min_pct, hr_zone4_max_pct,
+	hr_zone5_min_pct, hr_zone5_max_pct,
+	warmup_minutes, cooldown_minutes,
+	min_representative_pace_sec_per_km, min_representative_time_seconds,
+	pace_color, heart_rate_color, warmup_color, effort_color, recovery_color, cooldown_color,
+	main_line_tint_pct, background_darken_pct, target_brighten_pct,
+	created_at, updated_at
+`
+
+// GetProfile returns the profile row for userID.
+func (db *DB) GetProfile(ctx context.Context, userID int64) (Profile, error) {
+	var p Profile
+	err := db.QueryRowContext(ctx, `SELECT `+profileColumns+` FROM profiles WHERE user_id = ?`, userID).Scan(
+		&p.GarminEmail, &p.GarminPassword, &p.GarminConnectedAt, &p.RollingWindowDays, &p.BackfillHorizonDays, &p.MaxHeartRate, &p.RestingHeartRate,
+		&p.HRZone1MinPct, &p.HRZone1MaxPct, &p.HRZone2MinPct, &p.HRZone2MaxPct,
+		&p.HRZone3MinPct, &p.HRZone3MaxPct, &p.HRZone4MinPct, &p.HRZone4MaxPct,
+		&p.HRZone5MinPct, &p.HRZone5MaxPct,
+		&p.WarmupMinutes, &p.CooldownMinutes,
+		&p.MinRepresentativePaceSecPerKm, &p.MinRepresentativeTimeSeconds,
+		&p.PaceColor, &p.HeartRateColor, &p.WarmupColor, &p.EffortColor, &p.RecoveryColor, &p.CooldownColor,
+		&p.MainLineTintPct, &p.BackgroundDarkenPct, &p.TargetBrightenPct,
+		&p.CreatedAt, &p.UpdatedAt,
+	)
+	if err != nil {
+		return Profile{}, fmt.Errorf("get profile for user %d: %w", userID, err)
+	}
+	return p, nil
+}
+
+// UpdateProfile overwrites userID's profile row. Callers should read via
+// GetProfile first and modify the fields they intend to change, since this
+// replaces every column.
+func (db *DB) UpdateProfile(ctx context.Context, userID int64, p Profile) error {
+	_, err := db.ExecContext(ctx, `
+		UPDATE profiles SET
+			garmin_email=?, garmin_password=?, rolling_window_days=?, backfill_horizon_days=?, max_heart_rate=?, resting_heart_rate=?,
+			hr_zone1_min_pct=?, hr_zone1_max_pct=?, hr_zone2_min_pct=?, hr_zone2_max_pct=?,
+			hr_zone3_min_pct=?, hr_zone3_max_pct=?, hr_zone4_min_pct=?, hr_zone4_max_pct=?,
+			hr_zone5_min_pct=?, hr_zone5_max_pct=?,
+			warmup_minutes=?, cooldown_minutes=?,
+			min_representative_pace_sec_per_km=?, min_representative_time_seconds=?,
+			pace_color=?, heart_rate_color=?, warmup_color=?, effort_color=?, recovery_color=?, cooldown_color=?,
+			main_line_tint_pct=?, background_darken_pct=?, target_brighten_pct=?,
+			updated_at=datetime('now')
+		WHERE user_id = ?`,
+		p.GarminEmail, p.GarminPassword, p.RollingWindowDays, p.BackfillHorizonDays, p.MaxHeartRate, p.RestingHeartRate,
+		p.HRZone1MinPct, p.HRZone1MaxPct, p.HRZone2MinPct, p.HRZone2MaxPct,
+		p.HRZone3MinPct, p.HRZone3MaxPct, p.HRZone4MinPct, p.HRZone4MaxPct,
+		p.HRZone5MinPct, p.HRZone5MaxPct,
+		p.WarmupMinutes, p.CooldownMinutes,
+		p.MinRepresentativePaceSecPerKm, p.MinRepresentativeTimeSeconds,
+		p.PaceColor, p.HeartRateColor, p.WarmupColor, p.EffortColor, p.RecoveryColor, p.CooldownColor,
+		p.MainLineTintPct, p.BackgroundDarkenPct, p.TargetBrightenPct,
+		userID,
+	)
+	if err != nil {
+		return fmt.Errorf("update profile for user %d: %w", userID, err)
+	}
+	return nil
+}
+
+// MarkGarminConnected records the first time userID successfully
+// authenticates with Garmin. A no-op if already set, so it always reflects
+// the first connection, not the most recent one.
+func (db *DB) MarkGarminConnected(ctx context.Context, userID int64) error {
+	_, err := db.ExecContext(ctx, `UPDATE profiles SET garmin_connected_at = datetime('now') WHERE user_id = ? AND garmin_connected_at IS NULL`, userID)
+	if err != nil {
+		return fmt.Errorf("mark garmin connected for user %d: %w", userID, err)
+	}
+	return nil
+}