docs(workspace): record why tsconfig baseUrl cannot be dropped yet

TypeScript 7 removes `baseUrl`, and since TypeScript 5.0 the `paths` map no
longer needs it. Removing it from `tsconfig.base.json` nonetheless breaks
every library that depends on another library: Nx's buildable-library
executors write a generated tsconfig under `tmp/<projectRoot>/build/` whose
`paths` re-declare dependency entries as workspace-root-relative dist
outputs (`dist/libs/telemetry/browser`). Without a `baseUrl` those
non-relative values raise TS5090 and TypeScript discards the whole `paths`
map, so `render:build` and `cockpit-shell:build` fail to resolve
`@threadplane/telemetry/browser` and `@threadplane/cockpit-registry`.

Leave the option in place and record the blocker next to it so the next
attempt starts from the Nx side rather than re-deriving this.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: blove

tsconfig.base.json

@@ -15,6 +15,15 @@
     "noImplicitOverride": true,
     "noImplicitReturns": true,
     "noUnusedLocals": true,
+    // TypeScript 7 drops `baseUrl`, and since TypeScript 5.0 the `paths` below
+    // no longer need it (they resolve against this file's directory). It cannot
+    // go yet: Nx's buildable-library executors (`@nx/angular:package`,
+    // `@nx/js:tsc`) write a generated tsconfig under `tmp/<projectRoot>/build/`
+    // that re-declares `paths` with workspace-root-relative dist outputs such as
+    // `dist/libs/telemetry/browser`. Those entries are non-relative, so without a
+    // `baseUrl` TypeScript reports TS5090 and discards the whole `paths` map,
+    // and every library that depends on another library fails to compile.
+    // Removing this needs an Nx fix (or the Nx TS-solution setup) first.
     "baseUrl": ".",
     "paths": {
       "@threadplane/design-tokens": ["libs/design-tokens/src/index.ts"],