Add project deletion and secret editing to dashboard

[motatoes]

Adds the public API and dashboard half of project deletion, plus an explicit write-only secret replacement flow.

Key behavior:

• adds Project Settings with typed-name confirmation
• restricts project deletion to organization admins
• proxies DELETE /projects/:projectId through the public edge
• removes deleted project queries and returns to the project list
• adds Edit on configured secrets while keeping name and scope fixed

Depends on diggerhq/blue#44.

Verification:

• dashboard build and typecheck
• changed-file ESLint
• focused dashboard tests (10)
• managed-edge tests (37)

The repository-wide dashboard lint still reports unrelated pre-existing findings outside this change.