fix: harden runtime scheduling and notifications

[Pigbibi]

Summary

• derive heartbeat expectations from configured runtime targets and real exchange sessions instead of a single US-weekday assumption
• add grace-aware, scoped runtime-report checks so delayed publication does not create false missing-report alerts
• fail closed on runtime/Telegram delivery errors and preserve the terminal notification outcome for monitoring
• strengthen runtime-guard diagnostics without changing strategy selection or order decisions

Validation

• uv sync --locked --extra test
• uv run --no-sync ruff check --exclude external .
• uv lock --check
• PYTHONPATH=. PYTEST_DISABLE_PLUGIN_AUTOLOAD=1 uv run --no-sync python -m pytest -q
• 305 passed, 2 warnings, 15 subtests passed

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 7645a607dd

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 522d6f724e

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".