web: update to ESLint 9 (#10812)

* web: update to ESLint 9

ESLint 9 has been out for awhile now, and all of the plug-ins that we use have caught up, so it is
time to bite the bullet and upgrade.  This commit:

- upgrades to ESLint 9, and upgrades all associated plugins
- Replaces the `.eslintrc` and `.eslintignore` files with the new, "flat" configuration file,
  "eslint.config.mjs".
- Places the previous "precommit" and "nightmare" rules in `./scripts/eslint.precommit.mjs` and
  `./scripts/eslint.nightmare.mjs`, respectively
- Replaces the scripted wrappers for eslint (`eslint`, `eslint-precommit`) with a single executable
  that takes the arguments `--precommit`, which applies a stricter set of rules, and `--nightmare`,
  which applies an even more terrifyingly strict set of rules.
- Provides the scripted wrapper `./scripts/eslint.mjs` so that eslint can be run from `bun`, if one
  so chooses.
- Fixes *all* of the lint `eslint.config.mjs` now finds, including removing all of the `eslint`
  styling rules and overrides because Eslint now proudly leaves that entirely up to Prettier.

To shut Dependabot up about ESLint.

* Added explanation for no-console removal.

* web: did not need the old and unmaintained nightmare mode; it can be configured directly.

web/src/elements/controllers/ModalOrchestrationController.ts

@@ -98,7 +98,6 @@ export class ModalOrchestrationController implements ReactiveController {
         // Pop off modals until you find the first live one, schedule it to be closed, and make that
         // cleaned list the current state. Since this is our *only* state object, this has the
         // effect of creating a new "knownModals" collection with some semantics.
-        // eslint-disable-next-line no-constant-condition
         while (true) {
             const modal = knownModals.pop();
             if (!modal) {