Add Homey Energy Tab support for IQ Battery driver

[SerrII]

What this does

Adds proper Homey Energy Tab integration for the IQ Battery driver, so the
battery shows up in the Energy Tab / energy flow diagram instead of being
invisible there.

Changes in drivers/iqbattery/driver.compose.json:

• Replaced "energy": { "batteries": ["INTERNAL"] } with
  "energy": { "homeBattery": true, "meterPowerImportedCapability": ..., "meterPowerExportedCapability": ... }, since batteries is meant for
  devices that are themselves powered by a battery (e.g. sensors), not for
  home battery storage systems. homeBattery: true is the capability Homey
  expects for this device type.
• Added meter_power.charged and meter_power.discharged capabilities,
  wired up as meterPowerImportedCapability / meterPowerExportedCapability.

Changes in drivers/iqbattery/device.ts:

• Added an accumulateLifetimeMeter() helper that turns Enphase's
  daily-resetting "today" charge/discharge totals into a proper
  ever-increasing lifetime meter, as required by Homey's meter_power
  semantics (must never decrease/reset). It tracks the last seen "today"
  value in the device store and adds the delta on each poll, handling the
  midnight rollover (when today's value drops back to ~0) by treating the
  full new value as the delta.
• The existing iqbattery_charge / iqbattery_discharge capabilities
  (daily totals, for display) are left untouched.

measure_power (live charge/discharge wattage) is intentionally not
included yet — the previous attempt using latest_power was already
disabled because the values didn't match actual behaviour. Happy to help
investigate a reliable source for that in a follow-up if you can point me
at the right API field/endpoint.

Testing

Unfortunately I could not test this on an actual Homey yet: npm install
fails locally with a 401 error, because package-lock.json pins most
packages to https://npm.drenso.dev/... (what looks like an internal/
private registry), which I don't have access to as an external contributor.
Running npm install --registry=https://registry.npmjs.org/ after deleting
package-lock.json works around it locally, but I didn't want to touch the
lock file as part of this PR without checking with you first — let me know
if you'd like that as a separate PR.

Given that, please treat this as a draft that needs review/testing on a
real device before merging. Happy to adjust based on feedback.