ui/phase-19: legacy parser learns Your Groups / Your Fleets / Incoming Groups

The parity rule from ui/PLAN.md says every UI phase that decodes a
new Report field must extend the legacy converter in lockstep.
Phase 19 brings ship groups (LocalGroup / OtherGroup /
UnidentifiedGroup / IncomingGroup) and LocalFleet onto the wire-
compatible UI surface; this commit teaches
tools/local-dev/legacy-report to populate the three sections that
exist in the legacy text format:

  - "Your Groups" → []LocalGroup. Cargo type, load, fleet name,
    state, on-planet vs hyperspace position (origin / range) all
    decoded; LocalGroup.ID is synthesised deterministically from
    the per-report group index so re-running the converter
    produces byte-identical JSON. Speed is left zero — the legacy
    table doesn't expose it.
  - "Your Fleets" → []LocalFleet. Origin / range / state mirror
    the row layout used by Killer / Tancordia variants; gplus's
    state-less rows still resolve.
  - "Incoming Groups" → []IncomingGroup. Origin / destination
    names — and `#NN` by-id references — resolve against the
    parsed planet tables. Because the section can land before
    "Your Planets" in some engines, group / fleet / incoming rows
    are buffered and resolved in `parser.finish` after every
    planet is known.

Battles, OtherGroup (only ever in battle rosters), and
UnidentifiedGroup stay out of scope — README.md spells out what
remains not-derivable.

Adds Killer031–033 / TSERCON_Z032–033 / Tancordia036–039 fixtures
to the dg directory and exercises three of them through new
TestParseDg{Killer031,Tancordia037,KNNTS041} smoke tests, plus
inline tests for each new section parser. Drops the stale
KNNTS039.json artefact left over from Phase 18 development.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

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