feat: add watchers, additional assignees, and per-rule Slack labels to firewatch rules

[amp-rh]

Summary

Extends firewatch rules so CI failures produce richer Jira issues and Automation-friendly Slack routing without adding Slack tokens or webhooks to the firewatch workload.

• jira_watchers: list of emails; watchers are added after issue create (best effort; unresolvable users log a warning and are skipped).
• jira_additional_assignees: list of emails; sets the Red Hat Jira Additional Assignees field (customfield_10465) after create (best effort).
• slack_channel / slack_user: optional strings; firewatch adds Jira labels slack-channel:<name> (# stripped) and slack-user:<sanitized-email> (@ → -at-) so Jira Automation rules (for example Send web request to a Slack Workflow) can route notifications per rule.

!default for email lists: when jira_watchers or jira_additional_assignees contains !default, values are merged from FIREWATCH_DEFAULT_JIRA_WATCHERS / FIREWATCH_DEFAULT_JIRA_ADDITIONAL_ASSIGNEES (JSON arrays). Firewatch exits with an error if !default is used but the corresponding env var is missing or empty after parsing (stricter than optional defaults on some other fields).

Rule reference: docs/configuration_guide.md.

openshift-ci smoke replay (local)

• development/env.list.example lists env vars for replaying firewatch report against a completed Prow job.
• make smoke-openshift-ci runs scripts/smoke-openshift-ci-replay.sh (jira-config-gen + firewatch report with --keep-job-dir).

Tests and tooling

• E2E: synthetic job names and stubbed downloads to avoid collisions; cleanup helper for created issues; optional live assertions for labels and watcher/additional-assignee fields when JIRA_EMAIL is set.
• Unit tests updated for report output parity and rule behavior.
• Pre-commit: types-requests for mypy; e2e may load repo-root .env via python-dotenv.
• VS Code: default pytest args targeting tests/.

New rule fields

Field	Type	Jira behavior
jira_watchers	list of emails	Watcher API after create
jira_additional_assignees	list of emails	Additional Assignees (customfield_10465)
slack_channel	string	Label slack-channel:<channel>
slack_user	string	Label slack-user:<sanitized-email>

Test plan

• Unit tests for rule getters, Jira helpers, report wiring, and slack labels on issues
• E2E (live Jira): passing-label regression and rule-field smoke with stubbed Prow layout
• pre-commit run --all-files
• Reviewer sign-off

Resolves INTEROP-8865, INTEROP-8979

[openshift-ci]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all