Phase 2: cheap event streams

BridgeEvents subscribes the streams selected for tracking, economy, and cheat
detection: Login/Logout/AccountLogin, AccountGoldChange, ValidVendorPurchase/
Sell, PlacePlayerVendor, SkillGain, FameChange, KarmaChange, QuestComplete,
PlayerDeath, PlayerMurdered, OnKilledBy, FastWalk, OnPropertyChanged, Command,
and Before/AfterWorldSave.

Every handler runs on the Core thread inside the path that raised it, so each is
wrapped to never throw, does only Emit (which enqueues and returns), and never
mutates the args. Three of these are veto hooks and are read strictly:
AccountLogin (Accepted/RejectReason, and a plaintext Password we never emit),
FastWalk (Blocked), and the login decision path generally.

Testing on the live shard found that SkillGain fires for NPCs, hard: the first
boot emitted 115 skill.gain events in four seconds, all spawned creatures
grinding Meditation, zero players. That is the general rule here — most "player"
events also fire for NPCs — so SkillGain, FameChange, KarmaChange, and OnKilledBy
all filter to players on the Core thread before the socket. Gold, fame, karma,
and the save boundaries were fired through their real code paths and observed at
the stub sidecar; gold.change round-trips the platinum->gold conversion and
persists across restarts. Evidence in docs/PLAN.md §12.

Adds tools/scaffolding/BridgeEventProbe.cs (never deployed) which triggers those
events through real world mutations rather than synthetic Invoke calls.

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

tools/scaffolding/README.md

@@ -8,6 +8,11 @@ These two scripts produced the measured budget in `docs/PLAN.md` §1. They are k
 |------|--------------------------|------|
 | `BridgeSeeder.cs` | `Scripts/Custom/BridgeSeeder.cs` | Populates a synthetic world: 50 accounts, 150 characters, 30 houses, 30 player vendors with 40 listings each. |
 | `BridgeProbe.cs` | `Scripts/Custom/BridgeProbe.cs` | Times every read the plugin performs, on the Core thread. Read-only. |
+| `BridgeEventProbe.cs` | `Scripts/Custom/BridgeEventProbe.cs` | Fires gold/fame/karma/save events through their real code paths so the emit path can be verified without a game client. **Mutates the world and saves.** Flag: `EventProbeOnStart`. |
+
+## Deploy overwrites Bridge.cfg
+
+`deploy.ps1` copies `overlay/Config/Bridge.cfg`, which deliberately omits the scaffolding flags. So **every deploy strips `SeedOnStart` / `EventProbeOnStart` / etc.** Re-append the flag you need after deploying, or the probe silently does nothing on the next boot. (This bit once during Phase 2 testing.)
 
 ## Using them