Show and control cooling on the controller card

[thorwaler]

Companion to the integration cooling PR
(thorwaler/pool_controller_coolingmode). With the integration reporting
hvac_mode: cool / hvac_action: cooling, the card currently mislabels cooling as
Idle, lights the dial heating-red, and shows radiator glyphs. This adds cooling
display and an on-card heat/cool toggle.

⚠️ Please port to source before merging

The repo ships only the built main.js, so these commits edit the bundle directly. They're here as a working reference, not a clean merge. The changes should be
re-applied in the card's source and rebuilt, and the build must regenerate
main.js.gz (a stale gzip is served in preference to main.js and silently shadows
it. This cost me an hour of "why won't my change show up"). Diffs below describe the
exact behaviour to reproduce.

What changed

Status

• Add a cooling string to the status tables (en: "Cooling", de: "Kühlbetrieb";
  other languages fall back to en).
• Status-label logic recognises hvac_action of cooling/cool.

Icons (mirror the heating iconography)

• Active cooling → blue mdi:snowflake (instead of mdi:radiator).
• Idle/disabled → mdi:snowflake-off when mode is cool (mirrors the persistent
  mdi:radiator-off heating indicator, so a cooling indicator shows even when off).
• Unknown-value fallthrough → snowflake in cool mode.

Dial

• The "on" visual lights for hvac === "cool" as well as "heat".
• Fill/accent go blue (#2980b9) in cool mode instead of heating-red (#c0392b),
  for both the current-value fill and the target marker.

Heat/Cool toggle button

• New action button (data-action="heat-cool-toggle") that calls
  climate.set_hvac_mode on the controller's climate entity, flipping cool↔heat —
  mirroring the existing maintenance set_hvac_mode call.
• Reflects the current mode by colour/icon/label (blue "Cooling" / red "Heating" /
  neutral when off).

Implementation gotcha

There are two action-buttons markup blocks in the bundle — a static one and the
live one built with ${showPowerSavingButton ? …} conditionals. The button must be
added to the conditional/live block or it won't render.

Testing

Pointed at a climate entity in cool mode: off/idle shows greyed snowflake-off; cool
selected lights the dial blue; actively cooling shows the solid blue snowflake and the
status reads Cooling. Heating behaviour unchanged in heat mode.

[thorwaler]

Companion backend PR: lweberru/pool_controller#5 — adds the cool hvac_mode this card reflects. Merge/port that first, since the card only shows cooling once the integration reports hvac_action: cooling.