Dedup Garmin data storage, configurable chart colors, taxonomy fixes, sync/progression fixes

- Remove duplicated Garmin fields from storage; decode display-only fields
  (activity name/type, lap duration/HR, structured workout raw JSON) from
  RawJSON at API-response time instead of storing redundant columns
- Add a fully configurable chart color system (pace/HR main-line colors, 4
  effort-kind colors, tint/darken/brighten intensity knobs) under Profile >
  Chart colors
- Rename training types and fix their display order (Easy, Long, 60'/30'
  Threshold, Tempo, Intervals, MAS Test, Race) everywhere they're listed
- Add an Efficiency Factor progression metric; fix Progression chart axes to
  use tight non-zero-based domains, m:ss/km pace formatting, and rounded
  ticks instead of raw floating-point labels
- Expose the raw get_workout_by_id() payload in the raw-data viewer
  alongside activity/lap/detail JSON; enlarge the modal and shrink array
  indentation for readability
- Fix "last sync" reporting a meaningless activity count: record one
  combined sync run per manual "Sync now" and count genuinely new
  activities instead of re-listing whatever Garmin returned for the queried
  window
- Let a Review Queue activity be manually cleared back to Unclassified, and
  make "Reset all" available even while disconnected from Garmin

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

backend/internal/store/migrations/0017_chart_background_darken.sql

@@ -0,0 +1,5 @@
+-- How strongly (0-100) the effort-kind color is darkened for the phase
+-- background above the line -- see frontend's ExpectedVsActualChart
+-- darken(). Never mixed with the main line color, unlike the fill below the
+-- line (see main_line_tint_pct).
+ALTER TABLE profile ADD COLUMN background_darken_pct REAL NOT NULL DEFAULT 35;