chore: migrate to angular 22

[aydex]

Summary

Upgrades the frontend (app/mikane) from Angular 21.2.8 to 22.0.0, run via the
official ng update schematics. Also bumps TypeScript 5.9 → 6.0 (required by
Angular 22).

⚠️ Hold merge until angular-eslint ships a v22 release. The
@angular-eslint/* packages are pinned at 21.4.0 (latest available) against
Angular 22 core. Lint passes, but I'd rather align the toolchain before merging
than land a known version skew.

What changed

• @angular/* 21.2.8 → 22.0.0, @angular/cdk / @angular/material → 22.0.0
• typescript ^5.9.3 → ^6.0.3
• HttpClient backend: schematic added withXhr() to provideHttpClient
  (main.ts). Angular 22 makes fetch the default
  backend; withXhr() preserves the existing XHR behavior so nothing breaks.
• Change detection: schematic added explicit ChangeDetectionStrategy.Eager
  to 44 components. In v22 the old Default (CheckAlways) is deprecated and
  renamed to Eager — same enum value, identical behavior, no perf change.
• tsconfig: removed baseUrl (no longer an allowed field) and the now-invalid
  noUnusedLocals. Dropping baseUrl is why every src/... import was rewritten
  to a relative path — this accounts for the bulk of the diff. Unused-locals
  coverage is retained via @typescript-eslint/no-unused-vars: "error".

Diff note

144 files / +2793 −2289 looks large but is ~95% mechanical: the src/... →
relative-import rewrite plus prettier reflow. The only behavioral lines to
review are the withXhr() and Eager changes described above.

Verification

• ✅ npm run build — clean (5.3s, no warnings)
• ✅ npm run lint — all files pass
• ✅ npm run test — 561/561 pass (66 files)

Follow-ups (not in this PR)

• Re-evaluate dropping withXhr() for the fetch backend (only blocker is upload
  progress reporting — verify the avatar upload flow first).
• With zoneless CD already enabled, the 44 Eager/CheckAlways components are a
  candidate for incremental migration to signal-based OnPush.

[aydex]

Summary

Upgrades the frontend (app/mikane) from Angular 21.2.8 to 22.0.0, run via the
official ng update schematics, plus the matching angular-eslint 21.4.0 → 22.0.0
bump. Also moves TypeScript 5.9 → 6.0 (required by Angular 22).

This was previously waiting on an angular-eslint v22 release; that has now landed,
so the toolchain is fully aligned and the PR is ready.

What changed

• @angular/*, @angular/cdk, @angular/material 21.2.8 → 22.0.0
• @angular-eslint/* + angular-eslint 21.4.0 → 22.0.0
• typescript ^5.9.3 → ^6.0.3
• HttpClient backend: schematic added withXhr() to provideHttpClient
  (main.ts). Angular 22 makes fetch the default
  backend; withXhr() preserves existing XHR behavior so nothing breaks.
• Change detection: schematic added explicit ChangeDetectionStrategy.Eager
  to 44 components. In v22 the old Default (CheckAlways) is deprecated and
  renamed to Eager — same enum value, identical behavior, no perf change.
• tsconfig: removed baseUrl (no longer an allowed field) and the now-invalid
  noUnusedLocals. Dropping baseUrl is why every src/... import was rewritten
  to a relative path — this accounts for the bulk of the diff. Unused-locals
  coverage is retained via @typescript-eslint/no-unused-vars: "error".
• ESLint flat config (eslint.config.mjs),
  required by angular-eslint v22:
  • Switched the template block from the legacy
    compat.extends("plugin:@angular-eslint/template/...") shim (dropped in v22)
    to the native flat configs ...angular.configs.templateRecommended /
    ...templateAccessibility, matching how the TS block already worked. Removed
    the now-unused FlatCompat machinery.
  • v22's tsRecommended enables prefer-on-push-component-change-detection. Moved
    the pre-existing override (which was misplaced in the .html block and dormant
    under v21) into the TS block as "warn" — keeps the OnPush nudge visible
    without failing CI given the 44 Eager components above.

Diff note

The bulk of the line count is mechanical: the src/... → relative-import rewrite
plus prettier reflow. The only behavioral lines to review are the withXhr(),
Eager, and ESLint config changes described above.

Verification

All run on the full Angular 22 + angular-eslint 22 toolchain:

• ✅ npm run build — clean, no warnings
• ✅ npm run lint — 0 errors (44 prefer-on-push warnings, intentional)
• ✅ npm run test — 561/561 pass

Follow-ups (not in this PR)

• Re-evaluate dropping withXhr() for the fetch backend (only blocker is upload
  progress reporting — verify the avatar upload flow first).
• With zoneless CD already enabled, the 44 Eager/CheckAlways components are
  candidates for incremental migration to signal-based OnPush — the lint rule is
  set to warn to track this.