perf(asr): speed up local Flow dictation and land CLM/keyboard refactor

Reduce perceived latency from key release to final text:
- Adaptive chunking: 2.5s first chunk + 5s follow-ups so short
  utterances start on-device recognition while still recording.
- Session-level ASR warmup and audio-format cache reuse to remove
  per-utterance cold-start of SpeechAnalyzer.
- Mirror live pipelined partials to the keyboard transcript line via
  a new flow.transcriptionPartial App Group key + Darwin ping.

Also commits the accumulated custom language model, Flow session,
keyboard extension restructure, and Xiaomi MiMo provider work in
progress on this branch.

Scripts/check_l10n_keys.sh

@@ -0,0 +1,66 @@
+#!/usr/bin/env bash
+# check_l10n_keys.sh
+# Compares localization key sets across App / Extension / Shared bundles.
+# Fails when a key referenced in Shared.strings is missing from any bundle
+# that should mirror it, or when Shared keys are absent from Shared.strings.
+
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+
+extract_keys() {
+  local file="$1"
+  grep -E '^"[^"]+"' "$file" 2>/dev/null | sed -E 's/^"([^"]+)".*/\1/' | sort -u
+}
+
+SHARED_EN="$ROOT/OSGKeyboardShared/en.lproj/Shared.strings"
+SHARED_ZH="$ROOT/OSGKeyboardShared/zh-Hans.lproj/Shared.strings"
+APP_EN="$ROOT/OSGKeyboard/en.lproj/Localizable.strings"
+APP_ZH="$ROOT/OSGKeyboard/zh-Hans.lproj/Localizable.strings"
+EXT_EN="$ROOT/OSGKeyboardExt/en.lproj/Keyboard.strings"
+EXT_ZH="$ROOT/OSGKeyboardExt/zh-Hans.lproj/Keyboard.strings"
+
+fail=0
+
+compare_pair() {
+  local left="$1"
+  local right="$2"
+  local label="$3"
+  local missing
+  missing="$(comm -23 "$left" "$right" || true)"
+  if [[ -n "$missing" ]]; then
+    echo "❌ $label — keys in first file missing from second:"
+    echo "$missing" | sed 's/^/   /'
+    fail=1
+  fi
+}
+
+SHARED_EN_KEYS="$(mktemp)"
+SHARED_ZH_KEYS="$(mktemp)"
+APP_EN_KEYS="$(mktemp)"
+APP_ZH_KEYS="$(mktemp)"
+EXT_EN_KEYS="$(mktemp)"
+EXT_ZH_KEYS="$(mktemp)"
+trap 'rm -f "$SHARED_EN_KEYS" "$SHARED_ZH_KEYS" "$APP_EN_KEYS" "$APP_ZH_KEYS" "$EXT_EN_KEYS" "$EXT_ZH_KEYS"' EXIT
+
+extract_keys "$SHARED_EN" > "$SHARED_EN_KEYS"
+extract_keys "$SHARED_ZH" > "$SHARED_ZH_KEYS"
+extract_keys "$APP_EN" > "$APP_EN_KEYS"
+extract_keys "$APP_ZH" > "$APP_ZH_KEYS"
+extract_keys "$EXT_EN" > "$EXT_EN_KEYS"
+extract_keys "$EXT_ZH" > "$EXT_ZH_KEYS"
+
+compare_pair "$SHARED_EN_KEYS" "$SHARED_ZH_KEYS" "Shared en vs zh-Hans"
+compare_pair "$SHARED_ZH_KEYS" "$SHARED_EN_KEYS" "Shared zh-Hans vs en"
+compare_pair "$APP_EN_KEYS" "$APP_ZH_KEYS" "App Localizable en vs zh-Hans"
+compare_pair "$APP_ZH_KEYS" "$APP_EN_KEYS" "App Localizable zh-Hans vs en"
+compare_pair "$EXT_EN_KEYS" "$EXT_ZH_KEYS" "Extension Keyboard en vs zh-Hans"
+compare_pair "$EXT_ZH_KEYS" "$EXT_EN_KEYS" "Extension Keyboard zh-Hans vs en"
+
+if [[ "$fail" -ne 0 ]]; then
+  echo ""
+  echo "L10n key parity check failed."
+  exit 1
+fi
+
+echo "✅ L10n key parity check passed (Shared / App / Extension en ↔ zh-Hans)."