fix: pass time.Local (not time.UTC) to gocronometer parsers

Three call sites in cronoclient.Client hardcoded time.UTC when invoking
ExportServingsParsedWithLocation, ExportExercisesParsedWithLocation, and
ExportBiometricRecordsParsedWithLocation. The result was that every
RecordedTime emitted by these subcommands carried a UTC offset (`...Z`)
regardless of the host zone, in direct violation of the timezone
contract: https://github.com/quantcli/common/blob/main/CONTRACT.md#2-timezone-policy

Beyond the JSON cosmetic, this caused the markdown date-bucketing in
cmd/format.go (`r.RecordedTime.Format("2006-01-02")`) to compute the
wrong calendar day for any host west of UTC: a record logged at 9pm
local on day N bucketed one day late.

Fix: time.UTC → time.Local in all three calls.

Verified:
  $ crono-export servings --since 7d --format json | jq '.[0].RecordedTime'
  "2026-05-02T00:00:00-04:00"   # was "2026-05-02T00:00:00Z"

Closes #13.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Co-authored-by: Orca <help@stably.ai>

Author: DTTerastar

internal/cronoclient/client.go

@@ -39,7 +39,7 @@ func (c *Client) Logout() {
 
 // Servings returns parsed serving records (one row per food item logged).
 func (c *Client) Servings(ctx context.Context, rng DateRange) (any, error) {
-	recs, err := c.inner.ExportServingsParsedWithLocation(ctx, rng.Start, rng.End, time.UTC)
+	recs, err := c.inner.ExportServingsParsedWithLocation(ctx, rng.Start, rng.End, time.Local)
 	if err != nil {
 		return nil, fmt.Errorf("export servings: %w", err)
 	}
@@ -48,7 +48,7 @@ func (c *Client) Servings(ctx context.Context, rng DateRange) (any, error) {
 
 // Exercises returns parsed exercise records.
 func (c *Client) Exercises(ctx context.Context, rng DateRange) (any, error) {
-	recs, err := c.inner.ExportExercisesParsedWithLocation(ctx, rng.Start, rng.End, time.UTC)
+	recs, err := c.inner.ExportExercisesParsedWithLocation(ctx, rng.Start, rng.End, time.Local)
 	if err != nil {
 		return nil, fmt.Errorf("export exercises: %w", err)
 	}
@@ -57,7 +57,7 @@ func (c *Client) Exercises(ctx context.Context, rng DateRange) (any, error) {
 
 // Biometrics returns parsed biometric records (weight, body fat, etc.).
 func (c *Client) Biometrics(ctx context.Context, rng DateRange) (any, error) {
-	recs, err := c.inner.ExportBiometricRecordsParsedWithLocation(ctx, rng.Start, rng.End, time.UTC)
+	recs, err := c.inner.ExportBiometricRecordsParsedWithLocation(ctx, rng.Start, rng.End, time.Local)
 	if err != nil {
 		return nil, fmt.Errorf("export biometrics: %w", err)
 	}