[feat](trx-rs): keep a station log, and a layout to work the bands from

The logbook of issue #54, in the shape the proposal settled on.

A new crate, trx-logbook, holds the contact, the ADIF reader and writer, the
file, and the rules for telling one contact from two.  ADIF because it is the
only thing the ecosystem reads: LoTW, eQSL, Club Log, QRZ and every other
logger take it and nothing else, so a log that cannot write .adi cannot be
uploaded, confirmed or moved.  The reader is forgiving in the ways real files
are irregular -- lowercase tags, CRLF, missing header, unknown fields, a
declared length that is the only thing ending a value -- and carries what it
does not model through to the export, so a round trip does not strip what
another program wrote.

The file is JSON Lines, appended one line per contact.  A log is the one
thing here that cannot be regenerated, and the bookmark store's whole-file
dump would rewrite megabytes to log one contact and lose all of them if the
power went halfway; an append costs the record being written and no more,
which a test tears a line in half to prove.  Edits append revisions, deletes
append tombstones, and the file compacts when the superseded outnumber the
live.

The panel is its own tab and stands in every layout.  An entry opens with six
fields and no more -- frequency, mode, rig name, time, and the callsign and
locator of whatever decode it was started from.  A report stays empty: an FT8
SNR is not what was sent.  Times come from the server, because the browser
may be a phone in another timezone, and the panel says so when the two
disagree by more than a second.  Worked-before answers as a callsign is
typed.

A decode is not a contact, so the Log button on an FT8 or APRS row opens an
entry and logs nothing by itself.

The ham layout is the fifth operator layout, opening on the logbook with the
radio controls around it, offered only where the rig can transmit.

Two bugs found on the way, both in code written here: a frequency of a whole
number of megahertz ending in a zero rendered as a tenth of itself, in Rust
and in TypeScript alike, because trimming trailing zeros from "20.000000"
walks back through the point.  The API also sits under /api/logbook rather
than /logbook, so it cannot shadow its own page the way /bookmarks does.

Closes #54

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SyX26FCpMQxiBoC7r5K1A7
Signed-off-by: Stan Grams <sjg@haxx.space>

Cargo.toml

@@ -26,6 +26,7 @@ members = [
     "src/trx-server/trx-backend/trx-backend-ft450d",
     "src/trx-server/trx-backend/trx-backend-soapysdr",
     "src/trx-client",
+    "src/trx-client/trx-logbook",
     "src/trx-client/trx-frontend",
     "src/trx-client/trx-frontend/trx-frontend-http",
     "src/trx-client/trx-frontend/trx-frontend-http-json",