feat(train): each km announced on foot, each 5 km by bike (ADR 0030, D49)

Step 11 takes up what OpenTracks does that Train didn't (D49). 11a: a
recording announces each kilometre on foot and each 5 km by bike, never
on a rower, where the Record sheet's switch is on for the activity
(remembered in the person's announce.json, off at first): the distance,
the moving time, the split's pace or speed and the heart rate. The app
hands the recorder the words in its language; Announcer.kt counts the
moving time and the distance, Cues.kt speaks the line after a cue still
speaking.

Not tried on a phone yet.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

docs/adr/0030-halkyon-train.md

@@ -1100,6 +1100,43 @@ Strava. What was found, 27 Oct:
     phone no longer keeps a track with a tempo shows and plays nothing. Not tried on a
     phone yet: the crossfade, the ducking under the cues, the metronome's click, how
     steady the cadence feels.
+- **D49 What OpenTracks does that Train didn't** (recommended, the developer's; 29 Oct;
+  step 11, D1's "at least what OpenTracks does"):
+  - **Announcements every km on foot, every 5 km by bike** (11a), never on a rower: the
+    time, the distance, the last split's pace or speed and the heart rate where a strap
+    or the Loop sends one, switched on the Record sheet and remembered for each activity;
+    one due while a plan's or a route's cue speaks waits for it (over an interval chosen
+    on the sheet, or the figures chosen on a settings page Train doesn't have).
+  - **A workout goes out as GPX, TCX or FIT** (11b) from its page through the share
+    sheet: GPX 1.1 with Garmin's TrackPointExtension (heart rate, cadence), TCX (laps,
+    heart rate, cadence, power, a row's distance) and FIT (binary, what Strava, Garmin
+    and intervals.icu read best, laps and power included), each written in Dart and
+    tested against the formats' specifications (over text formats alone, which lose
+    FIT's readers' best import).
+  - **The barometer's air pressure is kept raw** (11c) as a series of its own,
+    `pressure`, where the phone has a barometer; the page works out elevation from it,
+    its changes from the pressure, its level from the GPS altitudes' median, and the
+    climb from that elevation (over correcting each fix as it is recorded, which would
+    lose the readings a better filter could use later).
+  - **A bike's speed and cadence sensor (CSC, 0x1816) and power meter (CPS, 0x1818)**
+    (11d), one of each chosen on the Record sheet as the strap is and remembered: the
+    wheel's speed gives the distance where GPS can't (a turbo trainer, a tunnel), the
+    wheel's circumference learnt from GPS on the first rides or typed in; the crank's
+    cadence and the watts are series (`bikeCadence`, `power`), live and on the page with
+    average and normalised power.
+  - Built: 11a. The words come from the app (`recorderAnnouncementsOf`, in
+    `announce_speech.dart`) in its language: the first hundred distances spelled out
+    (further on as digits), what each count of hours, minutes and seconds is said as,
+    and each sentence with its placeholder; the service (`Announcer.kt`, tested on the
+    JVM) counts the moving time and the distance the plan's measures keep (paused fixes
+    left out), and on each distance passed says it, the moving time (hours and minutes
+    after the first hour, else minutes and seconds), the split's pace or speed (the
+    number in the app's language) and the heart rate of the last 5 s; a jump past
+    several (GPS lost in a tunnel) says the last. Spoken without a tone, queued after a
+    cue that speaks; a cue that comes meanwhile cuts it short, as cues come first. Off
+    for every activity until switched on (`announce.json`, `AnnounceStore`, never
+    synced). Not tried on a phone yet: how it sounds over music, eSpeak's and
+    RHVoice's reading of the German sentences.
 
 ## Consequences