Add --build flag for git stack deploys

[TimElschner]

Summary

• Adds per-stack "Build images on deploy" toggle (default: true) so docker compose up includes --build when deploying git stacks via webhook, auto-update, or manual deploy
• Fixes the issue where containers with build: directives in their compose file were recreated from cached images — code changes were never deployed
• Flag threads through the entire deploy chain: DB → API → deployGitStack → deployStack → executeComposeCommand → executeLocalCompose / executeComposeViaHawser

Changes

Area	Files	What
DB Schema	schema/index.ts, schema/pg-schema.ts	build_on_deploy column (default true)
Migrations	drizzle/0004_*, drizzle-pg/0004_*	ALTER TABLE for SQLite + PostgreSQL
DB Functions	db.ts	GitStackData, createGitStack, updateGitStack
Deploy Chain	stacks.ts	--build in compose args + Hawser JSON body
Git Deploy	git.ts	Both deployGitStack and deployGitStackWithProgress
API	api/git/stacks/+server.ts, [id]/+server.ts	POST + PUT accept buildOnDeploy
Frontend	GitStackModal.svelte	TogglePill UI with Hammer icon
Tests	tests/stack-git-flow.test.ts	API-level tests for buildOnDeploy CRUD

Non-git stacks are unaffected

The build option only flows through when DeployStackOptions.build is explicitly set. Git stacks read it from gitStack.buildOnDeploy; all other stack types leave it undefined → no --build flag.

Test plan

• Create a git stack with default settings → verify buildOnDeploy: true in response
• Toggle "Build images on deploy" OFF → verify buildOnDeploy: false persists
• Deploy a git stack with build: in compose file → verify --build appears in compose command
• Deploy a git stack with buildOnDeploy: false → verify --build is absent
• Deploy a non-git stack → verify no --build flag (no regression)
• Test Hawser deploy path → verify JSON body includes build: true

🤖 Generated with Claude Code

[CLAassistant]

All committers have signed the CLA.

[jotka]

@TimElschner can you please remove claude from commits - we don't want Claude to be contributor in Dockhand. :)
(perhaps create a fresh PR)