Phase 7: telemetry and usage (daily rollup + week dashboard)

Build on Phases 1–6. Telemetry already arrived on
restrict/<device>/telemetry; this phase stores it in a daily rollup and
shows it.

- store: migration 003 adds telemetry_daily (device, day, app seconds,
  site seconds). InsertTelemetry maintains the affected days in the same
  transaction; RebuildRollups backfills and repairs it. UsageRange and
  TopUsage serve the week grid and top lists. CapAudit enforces the
  size-capped append-only audit log from AGENTS.md §7.
- web: GET /devices/{id}/usage — Monday-to-Sunday totals plus the top 10
  apps and top 10 sites, using CSP-safe native <progress> bars.
- theme.js: light/dark from the OS preference, with a nav toggle, loaded
  as an external script so the strict CSP still holds.
- cmd/control: `rollup` subcommand; rollup rebuild and audit cap at
  start-up and every 15 minutes.
- Version 0.5.0-phase7 (compose, Makefile, docs).

Tests: go test ./... and go vet ./... pass in golang:1.25-alpine.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

Makefile

@@ -1,5 +1,5 @@
-IMAGE ?= webrestrict/control:0.4.0-phase6
-BUILD_VERSION ?= 0.4.0-phase6
+IMAGE ?= webrestrict/control:0.5.0-phase7
+BUILD_VERSION ?= 0.5.0-phase7
 
 # Bounded docker helper for the Go toolchain. The container runs as the current
 # user, so the repository and the module cache stay owned by you.