feat(slack-gateway): add shared workspace routing flow

[onutc]

Summary

• add the Slack channel gateway, channel route resolution, and channel conversation upsert flow
• add deployment/build wiring and env templates for the staging Slack gateway
• preserve the latest OAuth callback failure logging and tests while carrying the full implementation branch

Testing

• cd integrations/slack-gateway && go test ./...
• cd api && go test ./...

[gitrank-connector]

👍 GitRank PR Analysis

Score: 5 points

Metric	Value
Component	Other (1× multiplier)
Severity	P3 - Low (5 base pts)
Final Score	5 × 1 = 5

Eligibility Checks

Check	Status
Issue/Bug Fix	❌
Fix Implementation	✅
PR Documented	✅
Tests	✅
Lines Within Limit	✅

Impact Summary

This PR adds a shared workspace routing flow for the Slack gateway and includes deployment/build wiring for staging. However, the actual code change shown is minimal—only 5 lines modified in a test file to add debug-level logging configuration. The PR description suggests broader implementation work, but the merged diff reflects only a test logging enhancement.

Analysis Details

Component Classification: This PR modifies test infrastructure for the Slack gateway integration, which doesn't fit into a specific high-impact category. The change is a test-level adjustment rather than a core feature or critical bug fix.

Severity Justification: This is a minor polish/test improvement (P3) rather than a bug fix or critical issue. The change adds debug-level logging to an existing test, improving observability without addressing a functional defect or security concern.

Eligibility Notes: issue=false: No bug or issue is being fixed; this is a feature addition. fix_implementation=true: The code change aligns with adding logging configuration to tests. pr_linked=true: Clear description provided with testing instructions. tests=true: Test file is modified. tests_required=true: Changes to test infrastructure and logging configuration warrant test verification to ensure logging works as intended.

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Analyzed by GitRank 🤖