fix(historian): map Boolean historization to Int2, not degenerate Int1 (#441)

The historian's Int1 analog-tag creation path is server-degenerate:
EnsureTags(Int1) stores an unusable stub (live-probed on the deployed
2023 R2 historian; root-caused + documented gateway-side in
HistorianGateway #11 / PR #16). HistorianTypeMapper mapped
DriverDataType.Boolean -> HistorianDataType.Int1, so Boolean historized
tags failed auto-provisioning.

Map Boolean -> Int2 instead (store 0/1). Int2 is a proven-creatable
analog type, and the value-write path already sends every value as a
double on WriteLiveValues regardless of tag type, so Boolean 0.0/1.0
round-trips cleanly. Both Float and Int2 are supported, so a
pre-existing Float Boolean tag retypes cleanly on its next deploy.

- HistorianTypeMapper: Boolean => Int2 (+ remarks)
- Unit pins: HistorianTypeMapperTests, GatewayTagProvisionerTests
  (Boolean_definition_carries_explicit_Int2_presence)
- Live gate: EnsureTags_boolean_sandbox_provisions_as_Int2 (was _Int1);
  retype probe reframed Float->Int2 (drops the dead Int1 leg)
- Docs: docs/Historian.md 'Boolean historization maps to Int2', CLAUDE.md,
  archreview STATUS.md (R2-06 live gate -> 6/6)

Resolves #441.

CLAUDE.md

@@ -319,11 +319,12 @@ When the section is disabled the applier binds the no-op `NullHistorianProvision
 run. Every dispatch logs a tally (`dispatched/requested/ensured/skipped/failed`); `dispatched=N` with
 `requested=0` flags the dormant no-op. The API key must carry `historian:tags:write` for `EnsureTags`. (PR
 #423 shipped `GatewayTagProvisioner` but left this wiring out, so provisioning was dormant; restored 2026-06-27.)
-**0.2.0 DataType delta (archreview 06/U-7):** `EnsureTags` is an **upsert** (create-or-update, not
-skip-if-exists), and the 0.2.0 `HistorianTagDefinition.DataType` proto3-optional change means Boolean tags now
-provision as **Int1** (0.1.0 silently defaulted them to Float). A pre-bump Float Boolean is asked to retype
-on its next deploy; the AVEVA-side retype policy is pinned by the live retype probe — see the "0.2.0 DataType
-provisioning delta" section in `docs/Historian.md`.
+**DataType mapping (issue #441):** `EnsureTags` is an **upsert** (create-or-update, not skip-if-exists).
+`HistorianTypeMapper` maps **`Boolean → Int2`** (Boolean historizes as a small 0/1 integer) because the
+historian's `Int1` analog-tag creation path is **server-degenerate** — `EnsureTags(Int1)` stores an unusable
+stub (live-probed; gateway-side resolution in HistorianGateway #11 / PR #16). Both Float and Int2 are
+supported analog types, so a pre-existing Float Boolean tag retypes cleanly to Int2 on its next deploy — see
+the "Boolean historization maps to Int2" section in `docs/Historian.md`.
 
 ### Gateway-side prerequisites
 
@@ -358,7 +359,7 @@ export HISTGW_GATEWAY_ENDPOINT=https://wonder-sql-vd03:5222   # absolute gateway
 export HISTGW_GATEWAY_APIKEY=histgw_<id>_<secret>             # must carry historian:read + historian:write (+ tags:write) scopes
 export HISTGW_TEST_TAG=<existing-tag>                         # read round-trip
 export HISTGW_WRITE_SANDBOX_TAG=<writable-float-tag>          # e.g. HistGW.LiveTest.Sandbox — write round-trip (EnsureTags + write)
-export HISTGW_BOOL_SANDBOX_TAG=<writable-bool-tag>            # e.g. HistGW.LiveTest.BoolSandbox — 0.2.0 Boolean EnsureTags leg + retype probe (06/U-7)
+export HISTGW_BOOL_SANDBOX_TAG=<writable-bool-tag>            # e.g. HistGW.LiveTest.BoolSandbox — Boolean→Int2 EnsureTags leg + retype probe (issue #441)
 export HISTGW_ALARM_SOURCE=<source-name>                      # alarm SendEvent → ReadEvents round-trip
 dotnet test --filter "Category=LiveIntegration"
 ```