apps-mcp: add templates for Lakeflow jobs & pipelines templates (#4183)

## Changes

This extends `apps-mcp` with jobs & pipeline initialization:
* Moved most of the`init_template.go` into `init_template/app.go`
* Added `init_template/{job,pipeline,empty}.go` and support for
respective templates
* Added generic AGENTS.md/CLAUDE.md for the new templates
* Updated associated prompts

## Why
We want to generalize `apps-mcp` to other resource types

## Tests

* Acceptance tests
* Manual and agent-based experiental validation

---------

Co-authored-by: Claude <[email protected]>

Author: lennartkats-db

acceptance/apps/init-template/app/out.test.toml

@@ -0,0 +1 @@
+✓ Template instantiation succeeded

acceptance/apps/init-template/app/output.txt

@@ -0,0 +1,4 @@
+#!/bin/bash
+$CLI experimental apps-mcp tools init-template app --name test_app --sql-warehouse-id abc123 --output-dir output > /dev/null 2>&1
+echo "✓ Template instantiation succeeded"
+rm -rf output

acceptance/apps/init-template/app/script

@@ -0,0 +1,2 @@
+Local = true
+Cloud = false

acceptance/apps/init-template/app/test.toml

@@ -0,0 +1 @@
+✓ Template instantiation succeeded

acceptance/apps/init-template/empty/out.test.toml

@@ -0,0 +1,4 @@
+#!/bin/bash
+$CLI experimental apps-mcp tools init-template empty --name test_empty --catalog main --output-dir output > /dev/null 2>&1
+echo "✓ Template instantiation succeeded"
+rm -rf output

acceptance/apps/init-template/empty/output.txt

@@ -0,0 +1,2 @@
+Local = true
+Cloud = false

acceptance/apps/init-template/empty/script

@@ -0,0 +1 @@
+✓ Template instantiation succeeded