fix: correct marker classifications per repo standard

Reclassify 4 markers that did not match their actual urgency per
docs/development.md:

  TODO → XXX (someday-maybe, no commitment):
    vendor/cordis/src/reflect.ts:250  — enhance error message
    packages/bash-local/src/run.ts:248 — stateful-shell design reference

  FIXME → TODO (should fix soon, not blocking release):
    vendor/loader/src/index.ts:108     — merge config
    vendor/cordis/src/fiber.ts:376     — internal/fiber-info

vendor/loader/src/index.ts

@@ -105,7 +105,7 @@ export class Loader extends EntryTree {
       // 1. set `fiber.entry`
       if (fiber.parent[Entry.key] && !fiber.entry) {
         fiber.entry = fiber.parent[Entry.key]
-        // FIXME merge config
+        // TODO merge config
         Inject.resolve(fiber.entry!.options.inject, fiber.inject)
       }