Task #222 partial — unblock AB Legacy PCCC via cip-path workaround (5/5 stages)

Replaced the "ab_server PCCC upstream-broken" skip gate with the actual
root cause: libplctag's ab_server rejects empty CIP routing paths at the
unconnected-send layer before the PCCC dispatcher runs. Real SLC/
MicroLogix/PLC-5 hardware accepts empty paths (no backplane); ab_server
does not. With `/1,0` in place, N (Int16), F (Float32), and L (Int32)
file reads + writes round-trip cleanly across all three compose profiles.

## Fixture changes

- `AbLegacyServerFixture.cs`:
  - Drop `AB_LEGACY_TRUST_WIRE` env var + the reachable-but-untrusted
    skip branch. Fixture now only skips on TCP unreachability.
  - Add `AB_LEGACY_CIP_PATH` env var (default `1,0`) + expose `CipPath`
    property. Set `AB_LEGACY_CIP_PATH=` (empty) against real hardware.
  - Shorter skip messages on the `[AbLegacyFact]` / `[AbLegacyTheory]`
    attributes — one reason: endpoint not reachable.

- `AbLegacyReadSmokeTests.cs`:
  - Device URI built from `sim.CipPath` instead of hardcoded empty path.
  - New `AB_LEGACY_COMPOSE_PROFILE` env var filters the parametric
    theory to the running container's family. Only one container binds
    `:44818` at a time, so cross-family params would otherwise fail.
  - `Slc500_write_then_read_round_trip` skips cleanly when the running
    profile isn't `slc500`.

## E2E + seed + docs

- `scripts/e2e/test-ablegacy.ps1` — drop the `AB_LEGACY_TRUST_WIRE`
  skip gate; synopsis calls out the `/1,0` vs empty cip-path split
  between the Docker fixture and real hardware.
- `scripts/e2e/e2e-config.sample.json` — sample gateway flipped from
  the hardware placeholder (`192.168.1.10`) to the Docker fixture
  (`127.0.0.1/1,0`); comment rewritten.
- `scripts/e2e/README.md` — AB Legacy expected-matrix row goes from
  SKIP to PASS.
- `scripts/smoke/seed-ablegacy-smoke.sql` — default HostAddress points
  at the Docker fixture + header / footer text reflect the new state.
- `tests/.../Docker/README.md` — "Known limitations" section rewritten
  to describe the cip-path gate (not a dispatcher gap); env-var table
  picks up `AB_LEGACY_CIP_PATH` + `AB_LEGACY_COMPOSE_PROFILE`.
- `docs/drivers/AbLegacy-Test-Fixture.md` + `docs/drivers/README.md`
  + `docs/DriverClis.md` — flip status from blocked to functional;
  residual bit-file-write gap (B3:0/5 → 0x803D0000) documented.

## Residual gap

Bit-file writes (`B3:0/5` style) surface `0x803D0000` against
`ab_server --plc=SLC500`; bit reads work. Non-blocking for smoke
coverage — N/F/L round-trip is enough. Real hardware / RSEmulate 500
for bit-write fidelity. Documented in `Docker/README.md` §"Known
limitations" + the `AbLegacy-Test-Fixture.md` follow-ups list.

## Verified

- Full-solution build: 0 errors, 334 pre-existing warnings.
- Integration suite passes per-profile with
  `AB_LEGACY_COMPOSE_PROFILE=<slc500|micrologix|plc5>` + matching
  compose container up.
- All four non-hardware e2e scripts (Modbus / AB CIP / AB Legacy / S7)
  now 5/5 against the respective docker-compose fixtures.

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

tests/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.IntegrationTests/AbLegacyReadSmokeTests.cs

@@ -17,8 +17,22 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.IntegrationTests;
 [Trait("Simulator", "ab_server-PCCC")]
 public sealed class AbLegacyReadSmokeTests(AbLegacyServerFixture sim)
 {
-    public static IEnumerable<object[]> Profiles =>
-        KnownProfiles.All.Select(p => new object[] { p });
+    // Only one ab_server container binds :44818 at a time and `--plc=SLC500` only
+    // answers SLC-mode PCCC, etc. When `AB_LEGACY_COMPOSE_PROFILE` is set, the theory
+    // filters to that profile alone so the suite matches the running container. Unset
+    // (the default for real-hardware runs) parameterises across every family the driver
+    // supports.
+    public static IEnumerable<object[]> Profiles
+    {
+        get
+        {
+            var only = Environment.GetEnvironmentVariable("AB_LEGACY_COMPOSE_PROFILE");
+            var profiles = KnownProfiles.All.Where(p =>
+                string.IsNullOrEmpty(only) ||
+                string.Equals(p.ComposeProfile, only, StringComparison.OrdinalIgnoreCase));
+            return profiles.Select(p => new object[] { p });
+        }
+    }
 
     [AbLegacyTheory]
     [MemberData(nameof(Profiles))]
@@ -26,9 +40,11 @@ public sealed class AbLegacyReadSmokeTests(AbLegacyServerFixture sim)
     {
         if (sim.SkipReason is not null) Assert.Skip(sim.SkipReason);
 
-        // PCCC PLCs use empty cip-path, but AbLegacyHostAddress still requires the
-        // /cip-path suffix to parse.
-        var deviceUri = $"ab://{sim.Host}:{sim.Port}/";
+        // PCCC semantics allow an empty cip-path (real SLC/PLC-5 hardware takes nothing
+        // after the `/`), but libplctag's ab_server requires a non-empty path at the
+        // CIP unconnected-send layer before the PCCC dispatcher runs. Default `1,0`
+        // against the Docker fixture; set AB_LEGACY_CIP_PATH= (empty) against real HW.
+        var deviceUri = $"ab://{sim.Host}:{sim.Port}/{sim.CipPath}";
         await using var drv = new AbLegacyDriver(new AbLegacyDriverOptions
         {
             Devices = [new AbLegacyDeviceOptions(deviceUri, profile.Family)],
@@ -58,9 +74,21 @@ public sealed class AbLegacyReadSmokeTests(AbLegacyServerFixture sim)
     {
         if (sim.SkipReason is not null) Assert.Skip(sim.SkipReason);
 
-        // PCCC PLCs use empty cip-path, but AbLegacyHostAddress still requires the
-        // /cip-path suffix to parse.
-        var deviceUri = $"ab://{sim.Host}:{sim.Port}/";
+        // Skip when the running compose profile isn't SLC500 — ab_server's `--plc=`
+        // flag selects exactly one family per process, so a write against a plc5-mode
+        // container with SLC500 semantics always fails at the wire.
+        var only = Environment.GetEnvironmentVariable("AB_LEGACY_COMPOSE_PROFILE");
+        if (!string.IsNullOrEmpty(only) &&
+            !string.Equals(only, "slc500", StringComparison.OrdinalIgnoreCase))
+        {
+            Assert.Skip($"Test targets the SLC500 compose profile; AB_LEGACY_COMPOSE_PROFILE='{only}'.");
+        }
+
+        // PCCC semantics allow an empty cip-path (real SLC/PLC-5 hardware takes nothing
+        // after the `/`), but libplctag's ab_server requires a non-empty path at the
+        // CIP unconnected-send layer before the PCCC dispatcher runs. Default `1,0`
+        // against the Docker fixture; set AB_LEGACY_CIP_PATH= (empty) against real HW.
+        var deviceUri = $"ab://{sim.Host}:{sim.Port}/{sim.CipPath}";
         await using var drv = new AbLegacyDriver(new AbLegacyDriverOptions
         {
             Devices = [new AbLegacyDeviceOptions(deviceUri, AbLegacyPlcFamily.Slc500)],