Add sample app CI validation for PROJ library installation

[Copilot]

Adds a CI step to build and run a sample application that validates the installed PROJ library works correctly. The sample performs a WGS84→UTM transformation and is packaged as a second artifact.

Changes

• sample_app/main.cpp - C++ application demonstrating coordinate transformation (Berlin: WGS84 → UTM Zone 33N). Validates output is within expected range and returns appropriate exit codes.

• sample_app/CMakeLists.txt - Build configuration using find_package(PROJ REQUIRED CONFIG) to link against installed library.

• build_sample.bat - Build script that configures, builds, tests, and packages the sample app using the install_proj output from the main build.

• .github/workflows/build_win.yml - Extended workflow to build sample app and upload as sample-app-windows artifact (executable + DLLs).

Example Usage

PJ *P = proj_create_crs_to_crs(ctx, "EPSG:4326", "EPSG:32633", NULL);
PJ *P_norm = proj_normalize_for_visualization(ctx, P);
PJ_COORD c_in = proj_coord(13.4050, 52.5200, 0, 0);  // Berlin
PJ_COORD c_out = proj_trans(P_norm, PJ_FWD, c_in);
// c_out.xy.x ≈ 391000, c_out.xy.y ≈ 5820000 (UTM Zone 33N)

The CI now produces two artifacts: the PROJ library installation and a working application that validates it.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Build sample app with simple wgs to utm conversion to check installed library</issue_title>
<issue_description>Add step to CI to try build sample app. It can utilize some unittest.
We want to have it as second artifact.</issue_description>

<agent_instructions>please provide pr with CI.
Use install space from CI wokflow. You can try to create second CI wokflow that depends on first one.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Build sample app with simple wgs to utm conversion to check installed library #1

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[michalpelka]

@copilot agreed with plan, proceed.

[michalpelka]

Ok, tiff is statically linked to proj_9_3.dll.
Can you try to simply ommit generated cmake config and link it manually?
@copilot