chore(release): repoint dig-store release source to DIG-Network/digs (#764)

[MichaelTaylor3d]

Summary

Part of the F2d reference sweep (#764): the GitHub repo DIG-Network/dig-store is being renamed to DIG-Network/digs, ahead of #1247 creating a NEW, unrelated DIG-Network/dig-store repo -- the moment that repo exists, GitHub's old->new redirect dies, breaking every stale DIG-Network/dig-store download URL. This installer builds those URLs at runtime (Repo::binary_url/latest_release_api), so it is the highest-priority fix (real-user installer breakage).

• Repo::dig_store() / Repo::dig_store_legacy() / Repo::digs() now target repo DIG-Network/digs (was dig-store).
• The binary/asset STEM is unchanged (dig-store, digstore, digs) -- this is a repo-location move only, not a CLI/binary rename (that's tracked separately, F2b).
• Updated the doc comments + unit-test mock release map/assertions to match.

Blast radius checked

Repo::dig_store()/dig_store_legacy()/digs() are consumed only within this crate (release.rs, update.rs, lib.rs -- confirmed via grep, no external consumers of these constructors). No wire/API contract changes; pure constant-value edit.

Test plan

• cargo build --lib clean
• cargo fmt --all -- --check clean
• cargo clippy --all-targets --all-features -- -D warnings clean
• cargo test --lib: 546 passed, 1 pre-existing unrelated failure (secure::tests::windows_verify_runs_on_a_program_files_dir_with_appcontainer_aces -- confirmed failing identically on main pre-change, a local Windows ACL/Get-Acl environment issue, not caused by this diff)
• Version bumped 0.29.2 -> 0.29.3 (patch -- no public API/behavior change, just a repo-URL constant)

Co-Authored-By: Claude noreply@anthropic.com