Dev: Rename "Project" to "TDM Plan" in Login Warning Toast

### Overview
Update user-facing "Project" terminology in the login warning popup to use the approved "TDM Plan" terminology.

### Details

This change was approved by stakeholders on 2026-06-09.

- Change `Only projects created after logging in can be saved`
- to `Only TDM Plans created after logging in can be saved`

Screenshot of Create Project page

### Action Items
- [ ] Assign yourself to the development issue.
- [ ] Move the development issue from the Prioritized Backlog to In Progress.
- [ ] Developer Changes:
- [ ] Note that this popup should appear any time the user is not logged in and is on the Create TDM Plan Wizard, but this is no longer working, so I'd like us to fix this problem as part of this issue. This has been broken for a while, possibly as a result of updating the NPM package that is used for the popup. At this time, I can only get the popup to show if I make a change to the TDM Plan in the wizard and then click on the Login link.
- [ ] Then make the text change requested.
- [ ] Create a PR, if applicable.
- [ ] Create a new slide (or edit one if it already exists) in staging and add the before and after images
- [ ] Once the PR has been approved, use it to close this issue. If there is no PR is associated with this issue, close this issue after lead signoff.

### Resources/Instructions
Related issue: #3199
- Staging Deck
- [2026-06-09, slide 46](https://docs.google.com/presentation/d/1PmFeErBaJ5C2pljGF8wG-OgxIUy6NYfXITvlod0KVl4/edit?slide=id.g3ea6cf237f1_0_847#slide=id.g3ea6cf237f1_0_847)
- Related document: [TDM_Calculator_System_Design_Full-draft](https://docs.google.com/document/d/1arL-qzN_6eZFJiYUWz1qSfHqTfDm5GjYw6MvmbVLbhg/edit?tab=t.42u1khvo5s6q)

#### Staging and Release decks
- [Staging Deck](https://docs.google.com/presentation/d/1crZ3IxqA4hAu3qzD7ns93Ieuqjwh6wyEtuX_46cP-fg/)
- [Staging slide, 3344](https://docs.google.com/presentation/d/1crZ3IxqA4hAu3qzD7ns93Ieuqjwh6wyEtuX_46cP-fg/edit?slide=id.g3f2afe8206d_0_51#slide=id.g3f2afe8206d_0_51)
- Release Deck
- [2025-MM-DD Release deck, slide ISSUE NUMBER]

Start by reproducing the login warning popup from the Create TDM Plan Wizard while logged out, then review related issue #3199 and the popup integration. Done means the popup appears without requiring a TDM Plan edit, and its message uses “TDM Plans” instead of “projects”.

Written by the indexing model from the issue text.