Task: Implement Hotfix: remaining CMake 4.4 uninitialized-variable warnings

Fix the remaining CMake 4.4.0 uninitialized-variable warnings not covered by PR #1664: two genuine use-before-define bugs, one dead-variable reference, and CPack/InstallRequiredSystemLibraries vendored-module noise.

• CMakeLists.txt: sprint_charts custom target no longer reads an uninitialized SPRINT variable — the SPRINT CACHE variable was removed entirely, since compass sprint charts already auto-detects the current sprint.
• CMakeLists.txt: dead DOGEN_VERSION reference replaced with CMAKE_PROJECT_VERSION.
• projects/CMakeLists.txt: flags initialised before first use.
• build/cpack/CMakeLists.txt: InstallRequiredSystemLibraries=/=CPack vendored-module uninitialized warnings suppressed narrowly around their two include() calls (CMake >= 4.4 only).
• Verified clean (no uninitialized warnings, no errors) against a real CMake 4.4.0 binary; full local build and ctest pass under CMake 4.3.4.

While fixing PR #1664's vcpkg-toolchain warning batch, a real CMake-4.4.0 configure surfaced four more uninitialized-variable warnings out of scope for that task: two genuine use-before-define bugs in our own CMake code, one dead-variable reference, and two more from CMake's own bundled CPack.cmake=/=InstallRequiredSystemLibraries.cmake modules (same vendored-module class as vcpkg's, different include() call site).

Fixed each:

• sprint_charts custom target: initially moved set(SPRINT 18 CACHE STRING ...) before add_custom_target(sprint_charts ...) so ${SPRINT} would resolve to 18 instead of empty, but that default was already six sprints stale (current sprint is 24). Removed the SPRINT CACHE variable entirely instead — see below.
• DOGEN_VERSION (a dead reference, likely a leftover from before the project's current name) replaced with CMAKE_PROJECT_VERSION, which is already used elsewhere in the same file.
• projects/CMakeLists.txt: added set(flags "") before first use — harmless in practice (CMake treats unset as empty) but exactly the class of bug warnings.uninitialized exists to catch.
• build/cpack/CMakeLists.txt: bracketed the two vendored-module include() calls individually with cmake_diagnostic(PUSH)=/=SET CMD_UNINITIALIZED IGNORE=/=POP, guarded for CMake >= 4.4, using the correct category token learned from PR #1664's review round (CMD_UNINITIALIZED, not uninitialized).

Verified directly against a real CMake 4.4.0 binary (downloaded via pip download cmake==4.4.0, same approach as PR #1664): fresh configure exits clean, zero uninitialized warnings or errors.

Removed the SPRINT CACHE variable entirely rather than bumping its stale default (18) to the current sprint (24): compass sprint charts already auto-detects the current sprint via current_version_sprint() when --sprint is omitted (cmd_sprint_charts in compass.py), so the CMake-side override was redundant and would only go stale again next sprint. Confirmed concretely — the generated build rule now invokes compass.sh sprint charts with no --sprint argument at all. Ran a full local build (compass build, exit 0) and ctest --preset linux-clang-debug-make (74/74 tests passed) under the local CMake 4.3.4 to confirm no regressions.

Manual QA scenarios (scaffolded via compass add test_scenario, run through the QA Validation Runner panel) that verify this task. Link new ones here as they're created; the scenario doc itself links back via its "Verifies task" field.

Fixed the four remaining CMake 4.4.0 uninitialized-variable warnings out of scope for PR #1664: removed the redundant/stale SPRINT CACHE variable entirely (sprint_charts now runs compass sprint charts with no arguments, which already auto-detects the current sprint), replaced the dead DOGEN_VERSION reference with CMAKE_PROJECT_VERSION, initialised flags in projects/CMakeLists.txt, and suppressed the CPack=/=InstallRequiredSystemLibraries vendored-module warnings narrowly around their include() calls (CMD_UNINITIALIZED, CMake >= 4.4 only). Verified against a real CMake 4.4.0 binary (clean configure, zero uninitialized warnings) and a full local build + ctest (74/74 passed) under CMake 4.3.4.