feat(fires): FRP intensity filter, confidence switch and six-stop color ramp (HAL-676)

Color every FIRMS detection by fire radiative power on the Portolan
cold → hot ramp (blue · teal · lime · amber · orange · red at
0 · 5 · 20 · 50 · 100 · 300 MW), replacing the three warm stops that
made a 2 MW and a 40 MW fire look alike. Heat cells, glow sprites and
card accents all read the same ramp (src/data/firmsIntensity.js).

Add a minimum-FRP log slider whose track is painted with the ramp (so
it doubles as the legend), an All / Nominal+ / High confidence switch
and an "N of M shown" counter to the Active Fires row. The filter runs
once in ingestion.applyFilter(), so markers, cards, heat cells, the
context store, the top-fires query and the analyst records all see one
set. Default is 0 MW / All: many of the strongest fires are rated low.

Persist both options in the layer state (token w: minFrp `f`,
confidence `c`), including the short share codec, and give the agent's
get_active_fires tool matching min_frp_mw / confidence arguments.

Layer panel gains generic `slider` and `segmented` row descriptors
(src/ui/rowFilterControls.js). New strings in es / ru / zh-CN.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

src/data/firmsLabels.test.mjs

@@ -9,11 +9,16 @@ import {
   formatFrpMw,
 } from './firmsLabels.js';
 
-test('FIRMS formatting helpers retain the shipped severity palette', () => {
-  assert.equal(accentForSeverity('red'), '224, 82, 82');
-  assert.equal(accentForSeverity('orange'), '240, 178, 62');
-  assert.equal(accentForSeverity('yellow'), '244, 227, 108');
-  assert.equal(accentForSeverity('chartreuse'), accentForSeverity('yellow'));
+test('FIRMS card accents are the six FRP ramp stops, coldest as the fallback', () => {
+  // Portolan hue order; blue #4a5bd4 … red #d1382a (HAL-675).
+  assert.equal(accentForSeverity('blue'), '74, 91, 212');
+  assert.equal(accentForSeverity('teal'), '57, 160, 168');
+  assert.equal(accentForSeverity('lime'), '201, 207, 74');
+  assert.equal(accentForSeverity('amber'), '242, 177, 52');
+  assert.equal(accentForSeverity('orange'), '232, 114, 44');
+  assert.equal(accentForSeverity('red'), '209, 56, 42');
+  assert.equal(accentForSeverity('yellow'), accentForSeverity('blue'));
+  assert.equal(accentForSeverity('chartreuse'), accentForSeverity('blue'));
 });
 
 test('FIRMS power that rounds to 10 MW drops the decimal', () => {