Add pub/sub channels for SSE (#1914)

[bpamiri]

Summary

• Adds channel-based pub/sub layer on top of existing SSE primitives (renders, streams, events all unchanged)
• In-memory adapter (Channel.cfc) — ConcurrentHashMap-backed, instant delivery, single-server
• Database adapter (DatabaseAdapter.cfc) — _wheels_events table with auto-create, poll-based, multi-server
• Global publish() function — call from controllers, models, jobs, anywhere
• Controller mixin (subscribeToChannel()) — long-lived SSE stream with heartbeats, timeout, disconnect detection
• JS client (wheels-sse.js) — zero-dependency EventSource wrapper with auto-reconnect + exponential backoff
• Tests — Channel engine core, DatabaseAdapter round-trip, controller mixin availability
• Docs — Full API reference at .ai/wheels/channels/channels.md

Files

File	Type	Purpose
vendor/wheels/Channel.cfc	New	Core in-memory pub/sub engine
vendor/wheels/channel/DatabaseAdapter.cfc	New	Database-backed adapter (auto-creates _wheels_events table)
vendor/wheels/controller/channels.cfc	New	Controller mixin (auto-loaded)
vendor/wheels/Global.cfc	Modified	publish() and $getChannelEngine()
vendor/wheels/public/assets/js/wheels-sse.js	New	JS client library (~120 lines)
vendor/wheels/tests/specs/controller/channelSpec.cfc	New	Channel engine + mixin tests
vendor/wheels/tests/specs/channel/DatabaseAdapterSpec.cfc	New	Database adapter tests
.ai/wheels/channels/channels.md	New	API docs + usage patterns

Closes #1914

Test plan

• CI passes — channel engine tests (in-memory subscribe/publish/unsubscribe, error isolation)
• CI passes — database adapter tests (publish/poll round-trip, channel filtering, lastEventId, cleanup)
• Controller mixin methods available on dummy controller
• Existing SSE tests still pass (no changes to sse.cfc)
• Manual: publish() from model callback delivers to subscribeToChannel() client

🤖 Generated with Claude Code

[github-actions]

Wheels Test Matrix

Engine	MySQL	PostgreSQL	SQL Server	H2	Oracle	SQLite
lucee5	✅	✅	✅	✅	❌ 6	✅
lucee6	✅	✅	✅	✅	❌ 6	✅
lucee7	❌ 55	❌ 55	❌ 55	❌ 55	❌ 61	❌ 55
adobe2018	✅	✅	✅	--	❌ 6	--
adobe2021	✅	✅	✅	--	❌ 6	✅
adobe2023	✅	✅	✅	--	❌ 6	✅
adobe2025	✅	✅	✅	--	❌ 6	✅
boxlang	✅	✅	✅	--	❌ 6	✅

Results for commit 0ac9e74.

[github-actions]

Wheels Test Results

    42 files  ±    0   3 780 suites  +84   25m 23s ⏱️ -43s
78 162 tests +1 260  77 403 ✅ +882  381 💤 ±0  338 ❌ +338  40 🔥 +40 
80 808 runs  +1 260  80 049 ✅ +882  381 💤 ±0  338 ❌ +338  40 🔥 +40 

For more details on these failures and errors, see this check.

Results for commit d468c09. ± Comparison against base commit e5e2d59.

♻️ This comment has been updated with latest results.