fix(deps): revert TS6/ESLint10/webpack-cli7 majors and gate future majors

Three Renovate-driven major bumps that landed via `nx affected`
passing trivially (deps-only change → no project flagged as
affected) have been silently breaking the build since they merged:

- **TypeScript 5→6** (#33) — TS6 deprecates `baseUrl`; every lib's
  `tsconfig.lib.json` now fails with `TS5101: Option 'baseUrl' is
  deprecated and will stop functioning in TypeScript 7.0`. Revert
  to TypeScript 5.9.x; we'll revisit when the broader Angular/Nx
  ecosystem aligns on TS6.
- **ESLint 9→10** (#36) — `@nx/eslint@22.7.1` was built against
  ESLint 9 and fails project-graph extraction with `Unable to find
  eslint`. Revert to ESLint 9.x; bring `@eslint/js`,
  `eslint-plugin-playwright`, and `jsonc-eslint-parser` back to
  their ESLint-9-compatible versions in the same revert.
- **webpack-cli 5→7** (#34) — webpack-cli 7 removed the
  `--node-env=production` flag that Nx's webpack target generates,
  breaking `portal-bff:build`. Revert to webpack-cli 5.x; revisit
  when Nx's webpack executor is updated.

The `ajv@<8.18.0` override added in #42 was over-broad: it forced
ESLint's transitively-bundled ajv to v8, which doesn't accept the
legacy options ESLint 9 passes. Narrow the override to
`@angular-devkit/core>ajv@<8.18.0` so only the targeted chain
(nestjs-prisma > @angular-devkit/core > ajv) is bumped, leaving
ESLint's ajv alone.

Verified locally: `pnpm exec nx run-many -t lint test build` is
green on all 8 projects; `pnpm audit --audit-level=moderate`
reports zero vulnerabilities.

To prevent future silent breakages, add a Renovate package rule
that gates **all major updates** behind the dependency dashboard
(`dependencyDashboardApproval: true`). Renovate stops creating PRs
for majors automatically — they appear as checkboxes in the
dashboard, and only get a PR when a human ticks the box. Patch
and minor bumps still flow on the daily cron.

`docs/development.md` "Reviewing Renovate PRs" is updated to
explain the gate and why it exists, citing the three offenders we
caught the hard way.

renovate.json

@@ -16,6 +16,11 @@
     "labels": ["security", "dependencies"]
   },
   "packageRules": [
+    {
+      "matchUpdateTypes": ["major"],
+      "dependencyDashboardApproval": true,
+      "description": "Major bumps require explicit approval via the dependency dashboard (tick the entry to release the PR). Auto-creating major PRs has caused silent build regressions: TypeScript 5→6, ESLint 9→10, and webpack-cli 5→7 all passed CI through `nx affected` (which sees a deps-only change as not affecting any project) and only surfaced when run-many was attempted locally. Forcing a human in the loop on majors prevents the same trap. Patch and minor bumps still flow automatically."
+    },
     {
       "groupName": "Angular",
       "matchPackageNames": [