legacy-report: parse battles + envelope JSON output

Side activity on top of Phase 27: the legacy-report tool now extracts
the "Battle at (#N) Name" / "Battle Protocol" blocks the parser used
to skip. Both the per-battle summary (Report.Battle: []BattleSummary)
and the full BattleReport (rosters + protocol) flow through.

Parser:
- new sectionBattle / sectionBattleProtocol states, with handle()
  trapping the per-race "<Race> Groups" sub-headers so the roster
  stays attributed to the right race;
- parseBattleHeader extracts (planet, planetName) from
  "Battle at (#NN) <Name>";
- parseBattleRosterRow maps the 10-token row into
  BattleReportGroup; column 8 ("L") is NumberLeft, confirmed against
  KNNTS fixtures;
- parseBattleProtocolLine counts shots and builds
  BattleActionReport entries from the 8-token "X Y fires on A B :
  Destroyed|Shields" lines;
- flushPendingBattle finalises a battle on next "Battle at" or any
  top-level section change and appends both the summary and the
  full report;
- syntheticBattleID(idx) + syntheticBattleRaceID(name) synthesise
  stable UUIDs in dedicated namespaces so re-runs produce
  byte-identical JSON.

Parse() signature widens to (Report, []BattleReport, error); the
single caller — the CLI — is updated.

CLI emits a v1 envelope:
  { "version": 1, "report": <Report>, "battles": { <uuid>: <BR>, ... } }
Bare-Report JSONs still load on the UI side for backward compat.

UI synthetic loader: loadSyntheticReportFromJSON detects the v1
envelope, decodes the report as before, and forwards every battle
through registerSyntheticBattle so the Battle Viewer resolves any
UUID offline. Pre-envelope JSON files (no `version` field) still
load — the battle registry stays empty for them.

Docs: legacy-report README moves Battles from "Skipped" to
in-scope, documents the envelope and UUID namespaces;
docs/FUNCTIONAL.md §6.5 (and the ru mirror) note that synthetic
mode is now end-to-end via the envelope.

Tests:
- TestParseBattles covers two battles with full rosters,
  per-shot destroyed/shielded mapping, NumberLeft from column 8,
  deterministic UUIDs across re-parses, and proves a trailing
  top-level section still parses (battle state closes cleanly);
- smokeWant gains a battles count; runSmoke cross-checks
  BattleSummary ↔ BattleReport alignment (id/planet/shots);
- all six real-fixture smoke tests pinned to their `Battle at`
  counts (28, 79, 56, 30, 83, 57);
- Vitest covers the synthetic-report envelope path (battles
  forwarded, missing-battles tolerated, bare-Report backward
  compat);
- KNNTS041.json regenerated against the new parser (existing
  diff was stale w.r.t. Phase 23 anyway; this commit brings it
  in line with the v1 envelope).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tools/local-dev/legacy-report/README.md

@@ -1,8 +1,25 @@
 # legacy-report-to-json
 
 Converts legacy text-format Galaxy turn reports (the *dg* and *gplus*
-engines that lived under `tools/local-dev/reports/`) into the JSON
-shape of [`pkg/model/report.Report`](../../../pkg/model/report).
+engines that lived under `tools/local-dev/reports/`) into a JSON
+envelope around [`pkg/model/report.Report`](../../../pkg/model/report)
+plus full `BattleReport`s (Phase 27).
+
+## Output envelope
+
+```jsonc
+{
+  "version": 1,
+  "report":  { /* report.Report */ },
+  "battles": { "<uuid>": { /* report.BattleReport */ }, ... }
+}
+```
+
+`version: 1` lets the UI distinguish a current-format envelope from a
+bare `Report` JSON. The synthetic-report loader accepts both — pre-
+envelope synthetic JSON files still load, just without battle
+fixtures. `battles` is omitted when the legacy file has no combat
+events.
 
 The output is consumed by the **DEV-only synthetic-report loader** on
 the UI client's lobby (`import.meta.env.DEV`). With it, the map view,
@@ -17,8 +34,8 @@ The tool is part of the synthetic-report parity rule documented in
 ```sh
 # from the repo root, with the Go workspace active
 go run ./tools/local-dev/legacy-report/cmd/legacy-report-to-json \
-    --in  tools/local-dev/reports/dg/KNNTS039.REP \
-    --out tools/local-dev/reports/dg/KNNTS039.json
+    --in  tools/local-dev/reports/dg/KNNTS041.REP \
+    --out tools/local-dev/reports/dg/KNNTS041.json
 ```
 
 `--in` reads `-` as stdin; `--out` defaults to stdout when empty or
@@ -68,6 +85,21 @@ already decodes from server responses
 | `LocalGroup[]`        | `Your Groups` (Phase 19)             |
 | `LocalFleet[]`        | `Your Fleets` (Phase 19)             |
 | `IncomingGroup[]`     | `Incoming Groups` (Phase 19)         |
+| `Battle[]` (summary)  | `Battle at (#N) Name` headers + `Battle Protocol` (Phase 27 follow-up) |
+
+The envelope's `battles` map carries the full `BattleReport`-s parsed
+out of the same blocks: every roster row turns into a
+`BattleReportGroup` (`Number`/`Tech`/`LoadType`/`LoadQuantity`/
+`NumberLeft`/`InBattle`), every `... fires on ... : Destroyed|Shields`
+line turns into a `BattleActionReport`. UUIDs are synthesised
+deterministically — `syntheticBattleID(idx)` for the battle
+identifier (per-report 0-based index, SHA1 namespace
+`be01a000-0000-0000-0000-000000000002`) and
+`syntheticBattleRaceID(name)` for `BattleReport.Races` entries (SHA1
+namespace `be01a000-0000-0000-0000-000000000003`). Re-running the
+converter on the same input file yields byte-identical JSON, so
+synthetic-mode UI URLs (`/games/synthetic-…/battle/<uuid>?turn=N`)
+stay stable across regenerations.
 
 Players whose name in the legacy file ends with `_RIP` are emitted with
 the suffix stripped and `Extinct: true`.
@@ -103,15 +135,9 @@ These exist in legacy reports but cannot be derived from the legacy
 text format at all. Each could become in-scope if a strong enough
 reason arises (see "Adding a new field" below).
 
-- Battles (`Battle at (#N) Name`, `Battle Protocol`) — the wire schema
-  carries battle UUIDs (`Report.Battle: []uuid.UUID`); the legacy text
-  carries per-battle rosters with stripped columns (no origin / range /
-  destination) and no stable identifier. Synthesising UUIDs from the
-  text would invent data that future Phase 27 work would have to drop;
-  the synthetic JSON therefore emits `battle: []`.
 - `OtherGroup[]` — no top-level legacy section. Foreign groups appear
-  only inside battle rosters (see above), with stripped columns; the
-  synthetic JSON emits `otherGroup: []`.
+  only inside battle rosters; the synthetic JSON emits
+  `otherGroup: []`.
 - `UnidentifiedGroup[]` — no legacy section at all; synthetic JSON
   emits `unidentifiedGroup: []`.
 - Cargo routes — no dedicated section in the legacy text format; the