fix(web): tutorials page throws when a tutorial's meeting time is not

[sakethsram8888]

Description

Fixes SJ-17: the Tutorials page threw and failed to render entirely whenever
a tutorial's meetingTime wasn't a valid "H:mm" string.

TutorialsComponent.shortTime() did meetingTime.split(':') and then
minutes.padStart(2, '0') with no guard. If meetingTime had no colon
(e.g. a convenor entered '9am'), minutes was undefined and the call
threw a TypeError. If meetingTime itself was undefined, it threw even
earlier on .split(':'). This ran once per row directly in the template
(tutorials.component.html:55) and again inside the Time-column sort
comparator, so a single malformed row took down the whole Tutorial List
screen for every student — not just that row.

shortTime is now total: it returns '' for a falsy input, returns the
raw string unchanged when there's no colon to parse, and only formats when
both an hour and minute part are present. No input can make it throw.

No API-side validation was added meeting_time is a free-text nullable
column by design at that layer, and only the create endpoint validates it,
not update. That's outside this card's scope.

Branches/commits this was built and tested against

• doubtfire-web: fix/sj-17 @ cfe74dc57, branched from origin/11.0.x @ 6e4c63064
• doubtfire-api: feature/mobile-notifications @ dc76a5a0e (note: not 11.0.x this repo's checkout was already on this branch and wasn't switched, since the fix is entirely client-side and doesn't touch the API)
• doubtfire-deploy: fix/local-dev-run @ ab6b0eb

How Has This Been Tested?

Unit tests src/app/projects/states/tutorials/tutorials.component.spec.ts (new file), run in isolation via:
ng test --include=src/app/projects/states/tutorials/tutorials.component.spec.ts --watch=false

Before/after reproduction of the exact original vs. fixed logic (standalone, outside the Angular app, to isolate just the function's behaviour):

Live manual verification, running the app locally against seeded data (COS10001):

• A normal tutorial list (well-formed times 15:30, 12:30) renders identically before and after this change.
• Seeded one tutorial's meeting_time to '9am' directly in the dev DB. With the fix applied, the Tutorial List page renders normally and shows 9am in the malformed row's Time column instead of crashing.
• Clicking the Time column header (which exercises the sort comparator's calls to shortTime) also does not throw with the malformed row present.
• Reverted the seeded data back to 15:30 afterward.

Note: the pre-fix crash itself was reproduced via the standalone script above (same logic, byte-identical to the original origin/11.0.x implementation) and confirmed by reading the code path, but was not separately re-demonstrated live in the running app with the fix reverted the live check above was done against the fixed code only.

One thing not covered by the automated test: that the malformed row visibly renders inline in the real table in the live app (rather than just that the pure function doesn't throw in isolation) this was checked manually, per above, not via an automated test.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Testing Checklist:

• Tested in latest Chrome
• Tested in latest Safari
• Tested in latest Firefox

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have requested a review from the relevant reviewers on the Pull Request