feat(automation): add proactive schedule loop

[gnanirahulnutakki]

Summary

• promote cron and standing-goals crates into the workspace
• add a durable proactive automation schedule model/store
• route due fires through a runtime abstraction with per-fire budget provisioning and attenuated cap-token validation
• deliver successful fires through a channel abstraction

Issue

• ARD-458

Scope note

This is a foundational ARD-458 slice. It does not close the whole epic: webhook-triggered paths, production channel integration, and full UX wiring remain follow-up work.

Verification

• cargo check -p ardur-automation -p ardur-cron -p ardur-standing-goals — passed
• cargo fmt --check — passed
• cargo test -p ardur-automation -p ardur-cron -p ardur-standing-goals — passed
• cargo clippy -p ardur-automation -p ardur-cron -p ardur-standing-goals --all-targets -- -D warnings — passed

Signed-off-by: Ardur team@ardur.ai

[linear-code]

ARD-458

[gnanirahulnutakki]

Required GitHub checks are green after the task-flow workspace overreach was removed from this ARD-458 slice, but merge is blocked by base branch policy. I attempted the allowed paths and did not use admin bypass.

Head: 375850c

Evidence:

• DCO — passed
• macos-latest / stable — passed
• ubuntu-latest / stable — passed

Local verification after the fix:

• cargo fmt --check — passed
• cargo test -p ardur-automation -p ardur-cron -p ardur-standing-goals — passed
• cargo clippy --workspace --all-targets -- -D warnings — passed

Merge attempts:

• gh pr merge 183 --rebase --delete-branch failed: base branch policy prohibits the merge.
• gh pr merge 183 --rebase --auto --delete-branch failed: auto-merge unavailable (enablePullRequestAutoMerge).
• I did not use --admin.

Leaving this PR open/In Review pending authorized review/merge.