refactor: remove server mode, router mode is now the only runtime path

[aaight]

Summary

Removes the server (single-process/fire-and-forget) execution mode, leaving only router mode as the sole runtime path. This eliminates ~400 lines of dead code and in-process queuing logic that was superseded by the BullMQ worker architecture.

Card: https://trello.com/c/69abfd306dcb3c2a6207feb8

What was changed

• Deleted src/index.ts + src/server.ts (monolithic entry point, replaced by src/router/index.ts)
• Deleted src/server/webhookReactionSender.ts (server-mode-only reaction sender)
• Deleted src/utils/webhookQueue.ts (in-process webhook queue, replaced by BullMQ/Redis)
• Deleted src/utils/activeCards.ts (in-process active card tracking, no longer needed)
• Deleted src/triggers/shared/webhook-queue.ts (in-process queue processor)
• Created src/webhook/ module with relocated webhook handler factory, parsers, logging helpers, and types from src/server/
• Simplified src/webhook/webhookHandlers.ts — router-only factory: always awaits processWebhook, errors propagate to Hono's error handler
• Simplified src/pm/webhook-handler.ts — removed isCurrentlyProcessing, enqueueWebhook, setCardActive/clearCardActive, processNextQueued and setProcessing calls
• Simplified src/triggers/github/webhook-handler.ts — same simplifications for GitHub webhook handler
• Simplified src/utils/lifecycle.ts — removed setProcessing/isCurrentlyProcessing exports
• Simplified src/utils/index.ts — removed re-exports for deleted utils
• Updated package.json — main, dev, start scripts now point to src/router/index.ts
• Updated .cascade/setup.sh, .cascade/ensure-services.sh, .cascade/env — added Redis setup and health check (required for router mode / BullMQ)
• Updated .env.example — added REDIS_URL documentation
• Updated CLAUDE.md, README.md — new three-service architecture, Redis prerequisite, updated directory structure

Test changes

• Deleted tests/unit/server.test.ts (server mode integration tests)
• Deleted tests/unit/utils/webhookQueue.test.ts (in-process queue tests)
• Deleted tests/unit/utils/activeCards.test.ts (active cards tests)
• Deleted tests/unit/triggers/webhook-queue.test.ts (webhook-queue processor tests)
• Deleted tests/unit/server/ (server-mode unit tests)
• Created tests/unit/webhook/webhookHandlers.test.ts — updated for router-only behavior
• Created tests/unit/webhook/webhookParsers.test.ts — relocated from tests/unit/server/
• Updated tests/unit/pm/webhook-handler.test.ts — removed server-mode tests
• Updated tests/unit/triggers/github-webhook-handler.test.ts — removed server-mode tests
• Updated tests/unit/utils/lifecycle.test.ts — removed setProcessing/isCurrentlyProcessing tests

Test plan

• All 3921 unit tests pass
• TypeScript type checking passes (zero errors)
• Lint passes (zero errors/warnings)
• src/router/index.ts is the sole entry point for the application

🤖 Generated with Claude Code

[nhopeatall]

Summary

Clean, well-organized removal of ~400 lines of dead server-mode code. One file was missed in the cleanup: src/webhook/webhookTypes.ts still contains the now-unused checkCapacity and fireAndForget properties and their JSDoc references. Everything else looks good — no dangling imports, CI passes, tests properly updated.

Code Issues

Should Fix

• src/webhook/webhookTypes.ts:64-82 — The WebhookHandlerConfig interface still declares checkCapacity?: boolean and fireAndForget?: boolean with their associated JSDoc, even though webhookHandlers.ts no longer destructures or uses these properties. The processWebhook JSDoc (lines 44-56) also still describes fireAndForget branching logic that was removed in this PR.

  Fix: Delete lines 64-82 (the two stale optional properties and their JSDoc) and simplify the processWebhook JSDoc to reflect router-only (always-await) semantics. Something like:

  /**
   * Processing callback. The handler awaits this callback before responding,
   * so 200 means "job queued." Errors propagate to Hono's error handler (500).
   *
   * May optionally return `WebhookLogOverrides` to enrich the webhook log entry.
   */

[nhopeatall]

LGTM — Clean removal of the server (single-process) execution mode. The refactoring is thorough and consistent:

• All in-process queuing logic (webhookQueue, activeCards, isCurrentlyProcessing/setProcessing) is fully removed from source, tests, and barrel exports — no stale references remain.
• The WebhookHandlerConfig interface is properly simplified: fireAndForget and checkCapacity options removed, leaving only the router-mode await path.
• Error handling in createWebhookHandler correctly logs to Sentry via handleProcessingError then re-throws to Hono's error handler — preserving the existing router behavior.
• The src/server/ → src/webhook/ rename cleanly separates shared webhook parsing/logging from the old monolithic server module.
• All 3921 unit tests pass, TypeScript compiles with zero errors, and CI is green.
• Documentation (CLAUDE.md, README.md, .env.example) and infrastructure scripts (.cascade/setup.sh, ensure-services.sh) are updated for the Redis/BullMQ dependency.