phase 1c-extract: typed kRPC service client + SpaceCenter extract

Built the missing piece that connects the ksp-bridge to a real KSP
instance via kRPC. This adds a typed service client on top of the
existing KRPCClient, plus the SpaceCenter-specific extraction logic
that pulls the universe state from a running KSP save.

@kerbal-rt/krpc-client
- types.ts — runtime representation of kRPC Type descriptors
  (TypeCode enum, KrpcType interface, decodeKrpcType, typeName)
- decoder.ts — kRPC value codec: primitive decode/encode, class refs,
  enums, collections (LIST/SET/TUPLE/DICTIONARY), system messages
  (STATUS/SERVICES/STREAM/EVENT/PROCEDURE_CALL). 34 unit tests.
- services.ts — ServiceCache built from KRPC.GetServices() response.
  Lookup by (service, procedure), enum value/name resolution. 12 tests.
- service-client.ts — KrpcServices: high-level invoke-by-name client.
  loadServices() helper to connect + load catalog. 9 integration tests
  with a mock kRPC server.
- schema.ts — added Set/Dictionary/Event/Expression types so the
  decoder can handle system messages without external .proto files.
  Also fixed a bug where 'STREAM' was being encoded as 0 due to
  protobufjs's nested-enum string lookup.

ksp-bridge
- extract.ts — the actual SpaceCenter calls. ~280 procedure calls
  per poll for a typical KSP save (UT, bodies, vessels, then per-body
  and per-vessel class methods in parallel). Build the UniverseSnapshot.
- krpc-adapter.ts — rewrote to use KrpcServices (typed) instead of
  the stub extract function. Supports an optional injected services
  for testing.
- bridge.ts — uses the new ExtractedState type and buildSnapshot.
- index.ts — connects to kRPC; falls back to mock mode if no server.
- convert.ts — backward-compat shim, re-exports from extract.ts.

The ksp-bridge can now talk to a real KSP install. We do NOT need
the kRPC mod's .proto files on disk — the server's GetServices()
response is the source of truth for type info. Documented the full
list of procedures we call, the kRPC value encoding, and the new
architecture in ksp/README.md.

Tests: 119 total, all green. Typecheck and build clean across all 11
projects.

Bonus: fixed an integer-overflow bug in the krpc-client connect()
handshake (was passing 'RPC'/'STREAM' strings to protobufjs; its
nested-enum string lookup silently encodes as 0, which made the
stream handshake send the wrong type. Switched to numeric codes.)

apps/tools/ksp-bridge/src/bridge.ts

@@ -13,8 +13,8 @@
  * The actual kRPC calls are in ./krpc-adapter.ts. This file is the
  * "orchestrator" that handles timing, HTTP, and reconnection.
  */
-import type { KRPCState } from './convert.js';
-import { buildSnapshot } from './convert.js';
+import type { ExtractedState } from './extract.js';
+import { buildSnapshot } from './extract.js';
 
 export interface BridgeOptions {
   /** API base URL, e.g. http://localhost:4000 */
@@ -24,7 +24,7 @@ export interface BridgeOptions {
   /** Polling interval in milliseconds (default 1000) */
   pollIntervalMs?: number;
   /** Function that returns the current KSP state, or null if KSP isn't ready */
-  getState: () => Promise<KRPCState | null>;
+  getState: () => Promise<ExtractedState | null>;
   /** Optional log function (defaults to console.log) */
   log?: (msg: string) => void;
   /** Optional error log function */