Adds the Offerings module and retargets the CI/CD pipeline to Api.SlpSoftware

Implements Unit 2 "Offerings" (backend module, admin CRUD UI with
drag-and-drop reordering, public GET /api/v1/offerings endpoint) and
executes the feature's D-15 CI/CD cutover, switching the deploy
pipeline's build/publish target from SlpModularCms.Api to
SlpModularCms.Api.SlpSoftware.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FWyStNL2ZsjrS7FLd7xvvN

aidlc-docs/features/slpsoftware-api/construction/slpsoftware-client-setup/code/summary.md

@@ -49,6 +49,8 @@ The Gitea Actions `backend-test` job (`.gitea/workflows/continuous_integration.y
 
 **Scope note**: `continuous_integration.yaml` is nominally owned by the `gitea-deployment-workflow` feature. This specific change (making the test gate pass for a test project this feature introduced) was judged in-scope to fix directly as Build-and-Test correctness — distinct from the actual deploy-target retarget (D-15), which remains deferred to this feature's own Operations phase.
 
+**Round 2**: the `services:` block above did not actually work in CI — the self-hosted runner (`raspberry-pi-arm64`) runs job and service containers in Docker host-network mode, so the `ports:` mapping was silently ignored and the service ended up on the host's own port 3306, which something else on the runner already answers on. Replaced with an explicit `docker run` step publishing on host port 3307 instead, plus a readiness loop using `mariadb-admin ping` (not `mysqladmin`, which this image doesn't provide — confirmed locally). Diagnosed from the actual Gitea Actions job log (fetched via the API) rather than guessed, and the replacement was verified locally end-to-end before pushing again.
+
 ## Build and Test Verification (Step 13.5)
 
 Two real build fixes were needed and applied during this step (not deviations from the plan — the plan didn't anticipate these, since they only surface once the code actually compiles):

aidlc-docs/features/slpsoftware-api/construction/slpsoftware-client-setup/infrastructure-design/deployment-architecture.md

@@ -3,6 +3,7 @@
 **Status note**: this diagram documents the **target state after** the Operations-phase cutover (D-15) — it is reference/planning context for Code Generation, not something this unit deploys itself. No infrastructure changes happen as part of this Construction stage.
 
 ```mermaid
+%%{init: {'themeVariables': {'primaryTextColor':'#000000','textColor':'#000000','tertiaryTextColor':'#000000'}}}%%
 graph TD
     visitor["Site Visitor / CMS Administrator browser"]
     proxy["Proxy Pi<br/>nginx + TLS (certbot)"]
@@ -40,6 +41,7 @@ Text alternative: a visitor's browser reaches the proxy Pi over HTTPS, which for
 ## Local Development (Current Scope of This Unit)
 
 ```mermaid
+%%{init: {'themeVariables': {'primaryTextColor':'#000000','textColor':'#000000','tertiaryTextColor':'#000000'}}}%%
 graph LR
     dev["Developer machine"]
     api["SlpModularCms.Api<br/>(existing dev host)"]