Support manual package fresh starts without moving release tags

[VolkerChristian]

Add a manual fresh package start for an existing version tag without creating, moving or deleting tags. A new run creates a new immutable source/tooling capture and package revision through the existing preparation path. Job retries continue to require the original artifact; a lost capture is recovered by starting a new manual run rather than mutating its old identity. Existing tag pushes and dependent-target requests keep their current semantics.

Files:

• ci/dispatch.py
• docs/maintainers.md
• tests/check_manual_package_workflows.py
• tests/test_handoffs.py
• tests/test_packaging.py

Verification:

• git diff --cached --check: passed.
• python3 <control>/tools/snodec_sync page-headers --repo . --check: passed.
• docs-audit --repo .: 0 violations.
• python3 tests/check_manual_package_workflows.py <snode.c workflow> <mqttsuite workflow>: both callers passed routing checks and 8 valid/invalid/injection tag-input cases each.
• SNODEC_TEST_TOOLING=<control> python3 -m unittest discover -s tests -v: all 78 cases executed; 76 passed, 1 existing real-OpenWrt-tools skip, 1 stale merged-symbol expectation initially failed. The stale expected published.svg was corrected while retaining all badge stability checks, and its focused rerun passed. All other suite cases passed.
• python3 -m unittest discover -s tests -p test_handoffs.py -v: 16 cases, 15 passed and 1 existing OpenWrt-tools skip; manual receiver tests reject wrong branch, repository, workflow, capture, attempt and dependent title.
• python3 -m unittest discover -s tests -p test_packaging.py -k test_status_render_is_immutable_and_does_not_copy_documentation -v: passed after expectation correction.

Receiver validates manual origin on the source repository’s API-reported default branch and its own run/capture ID, preserving the existing artifact and target-job checks. Maintainer docs also correct the stale navigation dependency reference to the actual .github@main implementation.

Production Python +6/-2 (net +4); test/check code +84/-1 (net +83). The extra manual event is explicitly requested; no new capture storage, retry reconstruction or signing implementation.

Merge DistributionPackages receiver before source callers. Central documentation: SNodeC/.github#27. No manual workflow dispatches, tag operations, settings changes or default-branch renames. The ongoing package chain keeps its original workflow definitions and captures.