feat(highlight): preset overhaul, categories, stats, theme colours, per-host profiles

Rules & engine:
- 22 presets (was 11): split status into okstate/warnstate/badstate, add delop,
  createop, danger, secret, level, exitcode, percent, http; status words are
  case-insensitive and cover the ✓ ✔ ✅ ✗ ✘ ✖ ❌ ⚠ symbol set
- value bands: the first number in a match picks the colour
  (percent: <20% red / 20-50% yellow / 50-80% light green / >=80% green)
- optional per-rule `caseInsensitive`, `category`, `bands`; load-time
  `refreshBuiltinRules` upgrades untouched built-in patterns in place

Settings page:
- three-way master switch `highlightMode` (all / basic / off); `basic` runs only
  the five safety+status rules and `off` empties the rule set rather than
  bypassing HighlightStream (which would drop the held tail)
- category column + grouping (`highlightGroupByCategory`), per-rule hit/duration
  stats (`highlightStats`, opt-in sink, snapshot once a second), theme-following
  colours (`highlightThemeColors`, hue-bucket mapping onto the ANSI palette),
  import/export JSON envelope, live preview through the real engine
- named rule subsets bound per host (`highlightPerHost` + `highlightProfiles`
  + `SshConnection.highlightProfileId`); empty ruleIds = every rule

Tests: new tests/hl-rules.mjs (word boundaries, case flag, negative words,
bands, import/export, preview, basic mode, categories, stats, theme colours,
profiles) + profile round-trip in tests/settings-store.mjs

package.json

@@ -12,7 +12,7 @@
     "build": "electron-vite build",
     "preview": "electron-vite preview",
     "typecheck": "tsc --noEmit -p tsconfig.node.json && tsc --noEmit -p tsconfig.web.json",
-    "test": "node tests/build-bundles.cjs && node tests/ssh-loopback.mjs && node tests/commands-store.mjs && node tests/settings-store.mjs && node tests/.hl-split-smoke.cjs && node tests/zmodem-e2e.mjs && node tests/ssh-session-e2e.mjs && node tests/sysinfo-e2e.mjs",
+    "test": "node tests/build-bundles.cjs && node tests/ssh-loopback.mjs && node tests/commands-store.mjs && node tests/settings-store.mjs && node tests/.hl-split-smoke.cjs && node tests/.hl-rules.cjs && node tests/zmodem-e2e.mjs && node tests/ssh-session-e2e.mjs && node tests/sysinfo-e2e.mjs",
     "dist": "electron-vite build && electron-builder --win msi nsis",
     "dist:dir": "electron-vite build && electron-builder --win --dir"
   },