Phase 4: character-profile request/response

BridgeProfile builds the read-models the website consumes; BridgeRequests
registers the inbound handlers. The sidecar asks, the shard answers on the Core
thread (inbound lines are marshaled through Timer.DelayCall before a handler
runs), so all of these read live world state safely.

  - char.request: resolve by serial, or by account + slot, and reply with a full
    profile (stats, all trained skills, worn equipment with flattened AOS mods,
    resists). Works for offline characters since a logged-off mobile stays
    resident until Delete.
  - account.roster: light per-character summary, offline chars included.
  - vendor.snapshot: every player vendor owned by an account, with held gold and
    priced listings.

Each request may carry a reqId the reply echoes so the sidecar can correlate.
An unresolvable request gets a bridge.error reply rather than silence, so the
website can show a real failure instead of hanging.

Verified against the real world with a sending stub: all five requests answered,
both char lookup paths (account+slot and serial) returning the identical profile,
vendor.snapshot returning seed_000's two vendors and 80 listings, and the bad
account returning bridge.error. Two real-data findings noted in docs/PLAN.md §14:
a GM character can have skill base > cap (the website must not assume otherwise),
and the mod-flattening path still wants a genuinely kitted character to exercise
against real suffix gear.

Adds tools/stub_sidecar_request.ps1 (sends requests) and a hardened
tools/stub_sidecar.ps1 (survives reaping/rebind).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tools/stub_sidecar.ps1

@@ -1,31 +1,45 @@
 param(
     [int] $Port = 7788,
-    [string] $Log = "$PSScriptRoot\sidecar_loop.log"
+    [string] $Log = "$PSScriptRoot\sc_robust.log"
 )
 
-$ErrorActionPreference = 'Stop'
-"[sidecar] listening on 127.0.0.1:$Port" | Out-File $Log -Encoding utf8
+# Robust stub sidecar: survives port-in-use from a just-killed instance, and never
+# dies on a transient error. Test scaffolding only.
+
+function Say($msg) {
+    for ($i = 0; $i -lt 5; $i++) {
+        try { "$msg" | Out-File -FilePath $Log -Append -Encoding utf8; return }
+        catch { Start-Sleep -Milliseconds 100 }
+    }
+}
+
+"" | Out-File -FilePath $Log -Encoding utf8
+Say "[sidecar] starting on 127.0.0.1:$Port"
 
 $listener = New-Object System.Net.Sockets.TcpListener([System.Net.IPAddress]::Loopback, $Port)
-$listener.Start()
+$listener.Server.SetSocketOption('Socket', 'ReuseAddress', $true)
+
+# Wait for the port to become bindable if a prior instance is still lingering.
+$bound = $false
+for ($i = 0; $i -lt 30 -and -not $bound; $i++) {
+    try { $listener.Start(); $bound = $true }
+    catch { Say "[sidecar] bind retry: $($_.Exception.Message)"; Start-Sleep -Seconds 1 }
+}
+if (-not $bound) { Say "[sidecar] could not bind $Port; giving up"; exit 1 }
+
+Say "[sidecar] listening"
 
 while ($true) {
     try {
         $client = $listener.AcceptTcpClient()
-        "[sidecar] === shard connected ===" | Add-Content $Log
-
-        $stream = $client.GetStream()
-        $reader = New-Object System.IO.StreamReader($stream)
-
-        while ($null -ne ($line = $reader.ReadLine())) {
-            "[sidecar] <- $line" | Add-Content $Log
-        }
-
-        "[sidecar] === shard disconnected ===" | Add-Content $Log
+        Say "[sidecar] === shard connected ==="
+        $reader = New-Object System.IO.StreamReader($client.GetStream())
+        while ($null -ne ($line = $reader.ReadLine())) { Say "[sidecar] <- $line" }
+        Say "[sidecar] === shard disconnected ==="
         $client.Close()
     }
     catch {
-        "[sidecar] error: $_" | Add-Content $Log
-        Start-Sleep -Milliseconds 200
+        Say "[sidecar] loop error: $($_.Exception.Message)"
+        Start-Sleep -Milliseconds 300
     }
 }