fix(tui): preserve resolved server directory

[jlongster]

Issue for this PR

User-reported regression: connecting the TUI to a remote server from a directory that does not exist on that server renders the UI but leaves prompt submission unusable. No linked issue.

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Startup already tries the client cwd and falls back to the server's default directory, but discarded that result when initializing the data provider. Pass the resolved directory into the provider and use it for the new-session command and new-tab action. Client-local filesystem paths remain unchanged.

How did you verify your code works?

• 143 tests passed across the affected TUI lifecycle, session-tab, new-session-location, data, composer, dialog, and form suites after rebasing onto v2.
• New renderer-level regression cases verify actual prompt submission with an accepted cwd and with a missing client cwd that falls back to the server default. Tab coverage verifies the resolved server directory is used instead of the client cwd.
• Prettier and git diff --check passed. Targeted lint completed with no errors.
• bun typecheck from packages/tui passes after rebasing onto current v2; the earlier upstream type error has been fixed.

Screenshots / recordings

No layout changes. The regression tests exercise the production TUI with its test renderer and an HTTP fixture server.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR