v1.20.0

This release fixes four bugs in how the agent reads dnf history and package
names, all of which silently corrupted or dropped data on the server side.

Fixes

• Truncated altered count. The regex slicing each dnf history list row
  ended in an unanchored lazy group, so the last column matched a single
  character: a transaction touching 22 packages was sent as 2. verify never
  caught it, since it compares transaction items rather than this field.
• Skipped transactions with dnf status flags. Dnf appends >, <, E,
  * and # to the Altered column to describe the transaction. Once the
  truncation above was fixed and the full column became visible, rows like
  1295 EE failed the row match and were dropped. The flags are now trimmed.
• Missing hostname package. GetHostname shelled out to /usr/bin/hostname,
  which belongs to the optional hostname package. On a minimal RHEL-family
  install both txlog build and txlog verify failed with a fork/exec error.
  It now uses os.Hostname.
• Epoch duplicated in the version field. SplitPackageName returned the
  epoch both in its own field and still glued to the version, so
  grub2-common-1:2.06-95.el9.noarch yielded epoch 1 and version 1:2.06.

Note for operators: packages with an epoch were recorded on the server
with the old version string. Until those transactions are re-sent, txlog verify will report them as differing — which is the correct reading of what
is stored.

Improvements

• make honors an ARCH variable (default amd64), so arm64 packages can be
  built for Raspberry Pi. nfpm.yaml takes the architecture from the same
  variable.
• All HTTP calls share a single authenticated client, so the transaction loop
  in txlog build reuses connections instead of dialing per request.
• /etc/os-release is parsed once into a map instead of being re-read per field.
• Go 1.26 idioms: errors.AsType (which also handles wrapped errors) and
  strings.SplitSeq.

Housekeeping

• Removed the orphaned internal/client package — 620 lines, roughly a quarter
  of the repository — left behind when internal/mcp, its only consumer, was
  deleted.
• Dropped dead fields from TransactionDetail and redundant bookkeeping in
  cmd.
• Added TestParseHistoryLine and TestSplitPackageName; neither parser had
  any coverage before.

Full Changelog: v1.19.1...v1.20.0