Deduplicate overlapping rules across contracts

Each rule now has one owning contract; others point to it:
validation and multi-step rules live in forms-validation (modal-workflows
references them), pagination metadata lives in go-api (table-management
references it), the async task flow lives in go-background-tasks (go-api
references it), backup git-safety checks live in backup-management
(go-database references it). Remove the leftover Vapor/Aqua baseline
mention and stale kit/patterns paths, compress the batch-file-upload ADR
narrative, and drop content-free pattern READMEs.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

rules/patterns/table-management/contract.md

@@ -1,6 +1,6 @@
 # Contract: Table Management (Shared)
 
-Version: 1.0
+Version: 1.1
 
 ## Scope
 
@@ -91,11 +91,9 @@ Canonical mapping:
 ## Pagination Rules
 
 - Pagination is server-side. Never load all rows and paginate client-side.
-- URL query parameters carry page state: `?page=2&per_page=50`.
-  - `page` is 1-based.
-  - `per_page` defaults to a fixed project constant (e.g. 50); user may change it from a fixed set
-    (25 / 50 / 100).
-- The server response includes: `total_count`, `page`, `per_page`, `total_pages`.
+- Query parameters and list response metadata follow the `go-api` contract.
+- `page` is 1-based; `per_page` defaults to a fixed project constant (e.g. 50) and may be
+  changed from a fixed set (25 / 50 / 100).
 - Display: "Showing 51–100 of 342" — always show the range and total.
 - Prev/Next buttons are disabled (not hidden) at the boundary pages.
 - Direct page-number input is optional; if present it clamps to `[1, total_pages]` on blur.