feat(tracking-page): settings screen for the customer tracking page

[roncodes]

PR 4 of the customer tracking pages refactor. It adds the settings screen at FleetOps → Settings → Tracking Page, plus an admin panel for the generic page's instance defaults.

Depends on #355 (the settings endpoints). This branch contains #355's commit, so until that merges this diff also shows the server change. I didn't stack the PRs, because merging a stacked PR's base closes it.

The screen

• Pages:
  • your own tracking page on or off;
  • its address under /t/, with a live availability check (debounced call to validate-slug) and copy and open links;
  • opting out of the shared page;
  • which page emails and labels link to.
• Branding:
  • display name, falling back to the organization name;
  • accent colour with a live contrast ratio (the text colour on it is derived automatically) and an optional dark-mode accent;
  • support phone, email and website;
  • "Powered by Fleetbase";
  • follow the device or always light;
  • default and enabled languages.
• Access:
  • status without verification;
  • SMS and email codes. SMS is disabled, with the reason shown, when the instance has no SMS provider;
  • how long a device stays verified;
  • customer sign-in and the account suggestion, shown only when the Customer Portal is installed.
• What verified customers see: toggles for each item, plus the privacy rules that always apply.
• Live preview: light and dark, themed from utils/tracking-page-theme. The tracking page itself (PR 5) will use the same tokens.

Settings load in the route's model() hook, not in a controller constructor.

Admin

A new "Tracking Page" panel under Fleet-Ops Config sets the generic page's instance defaults: on or off, display name, accent, support contacts and powered-by.

Also

• A sidebar item and a settings-hub card.
• tracking-page.settings.* translation keys in all 10 locales. Non-English files carry the English text until they're translated.

Not in this PR

• Uploading a separate logo: the page uses the organization logo, or a monogram when there's none.
• Tests: the addon has no ember test suite running in CI. ember.yml runs lint and build only, and the addon coverage work is still open in test(ember): drive addon/ coverage behind a per-file 100% gate #310.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (9ba5d0d) to head (4ef4dd8).
⚠️ Report is 11 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##                main      #357    +/-   ##
============================================
  Coverage     100.00%   100.00%            
- Complexity     12379     12452    +73     
============================================
  Files            600       601     +1     
  Lines          46496     46696   +200     
============================================
+ Hits           46496     46696   +200     

Flag	Coverage Δ
backend	100.00% <100.00%> (ø)

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