feat: add --last-partition flag to branch creation

[gnzjgo]

Closes #135

Adds --last-partition flag to tinybird build and tinybird dev commands, matching the tb branch create <name> --last-partition behavior from the platform CLI.

When a branch is created with this flag, the last partition of production data is copied into the branch.

Changes

• src/api/branches.ts: createBranch and getOrCreateBranch accept CreateBranchOptions with lastPartition flag, passed as last_partition=1 query param to POST /v1/environments
• src/cli/commands/build.ts: BuildCommandOptions passes lastPartition through to getOrCreateBranch
• src/cli/commands/dev.ts: DevCommandOptions passes lastPartition through to getOrCreateBranch
• src/cli/index.ts: --last-partition option added to build and dev commands

Usage

tinybird build --last-partition
tinybird dev --last-partition