Remove unnecessary type assertions across codebase

Add oxlint-tsgolint and configure typescript/no-unnecessary-type-assertion
to flag redundant `!` and `as Foo` casts. Type-aware mode is left off by
default to keep `npm run lint` fast; the rule sits configured for when we
turn type-aware on intentionally. Auto-fix removed ~283 redundant casts;
two manual touch-ups: a real tsgolint false positive in split-container.tsx
and a stale ChildProcess import after a double-cast collapsed.

packages/cli/src/commands/daemon/pair.ts

@@ -12,7 +12,7 @@ export function pairCommand(): Command {
   return addJsonOption(new Command("pair").description("Print the daemon pairing QR code and link"))
     .option("--home <path>", "Paseo home directory (default: ~/.paseo)")
     .action(async (_options: PairOptions, command: Command) => {
-      await runPairCommand(command.optsWithGlobals() as PairOptions);
+      await runPairCommand(command.optsWithGlobals());
     });
 }