fix(exchanges): restore type-check safety net and repair dead balance guards

tsconfig compiled docs/ (vendored ccxt samples) and @types/react was missing,
so 269 tsc errors buried the real ones. Scoping the project and adding the
missing type packages left 42 genuine errors in src/, which exposed two bugs:

- lighter: assertSpotBalance's buy branch and createOrder's spot-sell guard
  compared the {available, wallet} object against a number, so both guards
  were dead. Introduce SpotAssetBalance with a precomputed 'effective' field
  (Extract Class) and route all three call sites through it.
- offset-maker: the below-min-sell branch logged 'skip sell' but pushed the
  SELL order anyway, and pushed a possibly-null price. Both branches now
  match their working sibling.

Also: widen LighterOrder's is_ask/reduce_only to BooleanFlag (the wire format
flags.ts already parses), extract sellableBase (Extract Function, 3 copies),
delete two scripts importing a module that does not exist, add a typecheck
script. tsc --noEmit: 269 -> 0 errors; 218 tests still pass.

bun.lock

@@ -21,6 +21,8 @@
       },
       "devDependencies": {
         "@types/bun": "^1.3.9",
+        "@types/react": "^19",
+        "@types/ws": "^8.18.1",
         "oxlint": "^1.54.0",
         "vitest": "^4.0.18",
       },
@@ -208,6 +210,10 @@
 
     "@types/node": ["@types/node@24.5.2", "", { "dependencies": { "undici-types": "~7.12.0" } }, "sha512-FYxk1I7wPv3K2XBaoyH2cTnocQEu8AOZ60hPbsyukMPLv5/5qr7V1i8PLHdl6Zf87I+xZXFvPCXYjiTFq+YSDQ=="],
 
+    "@types/react": ["@types/react@19.2.17", "", { "dependencies": { "csstype": "^3.2.2" } }, "sha512-MXfmqaVPEVgkBT/aY0aGCkRWWtByiYQXo3xdQ8r5RzuFrPiRn8Gar2tQdXSUQ2GKV3bkXckek89V8wQBY2Q/Aw=="],
+
+    "@types/ws": ["@types/ws@8.18.1", "", { "dependencies": { "@types/node": "*" } }, "sha512-ThVF6DCVhA8kUGy+aazFQ4kXQ7E1Ty7A3ypFOe0IcJV8O/M511G99AW24irKrW56Wt44yG9+ij8FaqoBGkuBXg=="],
+
     "@vitest/expect": ["@vitest/expect@4.0.18", "", { "dependencies": { "@standard-schema/spec": "^1.0.0", "@types/chai": "^5.2.2", "@vitest/spy": "4.0.18", "@vitest/utils": "4.0.18", "chai": "^6.2.1", "tinyrainbow": "^3.0.3" } }, "sha512-8sCWUyckXXYvx4opfzVY03EOiYVxyNrHS5QxX3DAIi5dpJAAkyJezHCP77VMX4HKA2LDT/Jpfo8i2r5BE3GnQQ=="],
 
     "@vitest/mocker": ["@vitest/mocker@4.0.18", "", { "dependencies": { "@vitest/spy": "4.0.18", "estree-walker": "^3.0.3", "magic-string": "^0.30.21" }, "peerDependencies": { "msw": "^2.4.9", "vite": "^6.0.0 || ^7.0.0-0" }, "optionalPeers": ["msw", "vite"] }, "sha512-HhVd0MDnzzsgevnOWCBj5Otnzobjy5wLBe4EdeeFGv8luMsGcYqDuFRMcttKWZA5vVO8RFjexVovXvAM4JoJDQ=="],
@@ -260,6 +266,8 @@
 
     "convert-to-spaces": ["convert-to-spaces@2.0.1", "", {}, "sha512-rcQ1bsQO9799wq24uE5AM2tAILy4gXGIK/njFWcVQkGNZ96edlpY+A7bjwvzjYvLDyzmG1MmMLZhpcsb+klNMQ=="],
 
+    "csstype": ["csstype@3.2.3", "", {}, "sha512-z1HGKcYy2xA8AGQfwrn0PAy+PB7X/GSj3UVJW9qKyn43xWa+gl5nXmU4qqLMRzWVLFC8KusUX8T/0kCiOYpAIQ=="],
+
     "delayed-stream": ["delayed-stream@1.0.0", "", {}, "sha512-ZySD7Nf91aLB0RxL4KGrKHBXl7Eds1DAmEdcoVawXnLD7SDhpNgtuII2aAkg7a7QS41jxPSZ17p4VdGnMHk3MQ=="],
 
     "dotenv": ["dotenv@17.3.1", "", {}, "sha512-IO8C/dzEb6O3F9/twg6ZLXz164a2fhTnEWb95H23Dm4OuN+92NmEAlTrupP9VW6Jm3sO26tQlqyvyi4CsnY9GA=="],