chore(workspace): tsconfig composite refs + axe-linter false-positive config (#147)

## Summary

Three editor-noise sources flagged by the VS Code TypeScript service + the Deque axe Linter extension, each tamed at the right layer. No runtime behaviour change.

| Source | Fix |
| --- | --- |
| **TS6306** — Referenced project `libs/{shared/ui,shared/state,feature/auth}` must have `composite: true`. Nx 22's lib generator doesn't emit `composite`; modern VS Code TS service flags it. | Add `composite: true` to each lib's `tsconfig.lib.json`, let `nx sync` redirect consumer references in `apps/portal-{shell,admin}/tsconfig.app.json` to point at the `.lib.json` directly. |
| **TS6504** — `moduleResolution: "node"` / `"node10"` deprecated, removed in TS 7.0. Two hits on the BFF tsconfigs. | Add `ignoreDeprecations: "5.0"` on `apps/portal-bff/tsconfig.{app,spec}.json` — the opt-out knob the diagnostic itself suggests. A proper migration to `nodenext`/`node16` is a separate chantier. |
| **axe-core/list (WCAG 1.3.1)** — `<ul>` "must only directly contain `<li>`, `<script>`, or `<template>`" — fires on Angular 17+ `@for` blocks inside lists. Pure static-linter limitation; rendered DOM is fine. | New `.axe-linter.yml` at repo root: `global-disable: [list]`. |

## What lands

### `composite: true` on lib `.lib.json`

[`libs/shared/ui/tsconfig.lib.json`](libs/shared/ui/tsconfig.lib.json), [`libs/shared/state/tsconfig.lib.json`](libs/shared/state/tsconfig.lib.json), [`libs/feature/auth/tsconfig.lib.json`](libs/feature/auth/tsconfig.lib.json) get `composite: true` added. `nx sync` then automatically rewrites consumer references:

```diff
- "path": "../../libs/shared/ui"
+ "path": "../../libs/shared/ui/tsconfig.lib.json"
```

in [`apps/portal-shell/tsconfig.app.json`](apps/portal-shell/tsconfig.app.json) and [`apps/portal-admin/tsconfig.app.json`](apps/portal-admin/tsconfig.app.json). Semantically cleaner — the app references the lib's actual compile config (which produces the `.d.ts` it consumes), not the lib's solution-style root tsconfig.

**Earlier attempt — composite on the solution `tsconfig.json` — silently broke `vitest`**: the Angular Vite plugin chokes on a composite project with `files: []` / `include: []` and falls through, leaving spec files loaded but tests not registered (`"No test suite found in file"`). Moving `composite` to `.lib.json` (the project that actually has inputs) fixes the contract without poking the plugin.

### `ignoreDeprecations: "5.0"`

[`apps/portal-bff/tsconfig.app.json`](apps/portal-bff/tsconfig.app.json) and [`apps/portal-bff/tsconfig.spec.json`](apps/portal-bff/tsconfig.spec.json) — silences `Option 'moduleResolution=node10' is deprecated and will stop functioning in TypeScript 7.0`. The diagnostic suggests `"6.0"` as the value, but TS 5.9 (our pinned version) only accepts `"5.0"`; using `"6.0"` results in `TS5103: Invalid value for '--ignoreDeprecations'` and breaks every spec. `"5.0"` is the current-gen accepted value.

The deprecation is real — TS 7.0 will drop both `"node"` and `"node10"` `moduleResolution` modes. The migration target is `moduleResolution: "nodenext"` paired with matching `module: "nodenext"`, but that interacts non-trivially with Nest's CommonJS pipeline and the BFF's import semantics. Out of scope for a drive-by fix; we'll handle it as a dedicated chantier when TS 7.0 lands on the roadmap.

### `.axe-linter.yml`

New file at repo root:

```yaml
global-disable:
  - list
```

The Deque axe Linter VS Code extension reads `.axe-linter.yml` at workspace root. The `list` rule (WCAG 1.3.1) fires false positives on Angular 17+ control-flow syntax — `@for (item of list; ...) { <li>… }` looks like a non-`<li>` child of `<ul>` to a static HTML scanner. The Angular compiler erases those tokens at build time; the rendered DOM is compliant. CI accessibility coverage is provided by `axe-playwright` per [ADR-0016 §"Tooling"](docs/decisions/0016-accessibility-baseline-wcag-aa-targeted-aaa.md) — it runs against the rendered DOM and is unaffected by this disable.

## Notes for the reviewer

- **Why not `composite: true` on every lib?** Per CLAUDE.md "no premature abstractions" — `libs/shared/{tokens,util}` are not currently referenced by any `tsconfig.app.json`, so they don't trigger TS6306. Adding `composite` to them would be future-proofing without a current consumer. When a consumer reference is added, the same one-line fix lands then.
- **Why not migrate `moduleResolution` properly?** The BFF runs on Nest's CommonJS pipeline; `nodenext` brings stricter ESM resolution (`.js` extensions in imports, package `exports` map enforcement) that ripples through. Not a 5-minute change. The `ignoreDeprecations` knob is the textbook defer mechanism for exactly this case.
- **Why disable `list` globally rather than per-file?** The rule's false-positive pattern (`<ul><@for>` / `<ol><@for>`) applies workspace-wide; we use `@for` consistently across `portal-shell` + `portal-admin`. Per-file disables would multiply as new templates land. axe-playwright remains the authoritative check on the rule.

## Test plan

- [x] `pnpm nx run-many -t lint test build --projects=portal-shell,portal-admin,portal-bff,shared-ui,shared-state,feature-auth` — 18/18 tasks pass. **517 specs green** across the affected projects.
- [x] `pnpm nx sync:check` — workspace in sync after the changes; running `sync` again is a no-op.
- [ ] Editor smoke — reopen the workspace in VS Code: the TS6306 errors on lib `tsconfig.json` files should be gone, the two `moduleResolution=node10` deprecation lines on BFF tsconfigs should be silenced, and the `list` rule under `sidebar.html` (`portal-admin`) should no longer surface.

---------

Co-authored-by: Julien Gautier <julien.gautier@apf.asso.fr>
Reviewed-on: #147

libs/feature/auth/tsconfig.lib.json

@@ -1,6 +1,7 @@
 {
   "extends": "./tsconfig.json",
   "compilerOptions": {
+    "composite": true,
     "outDir": "../../../dist/out-tsc",
     "declaration": true,
     "declarationMap": true,

libs/shared/state/tsconfig.lib.json

@@ -1,6 +1,7 @@
 {
   "extends": "./tsconfig.json",
   "compilerOptions": {
+    "composite": true,
     "outDir": "../../../dist/out-tsc",
     "declaration": true,
     "declarationMap": true,

libs/shared/ui/tsconfig.lib.json

@@ -1,6 +1,7 @@
 {
   "extends": "./tsconfig.json",
   "compilerOptions": {
+    "composite": true,
     "outDir": "../../../dist/out-tsc",
     "declaration": true,
     "declarationMap": true,