Reimplement issue dependencies on go-github v89 REST API (#2839)

* Reimplement issue dependencies on go-github v89 REST API

Issue dependencies (blocked_by / blocking) were implemented on GraphQL via
githubv4. Because the pinned githubv4 library predates the dependency
mutations, the code hand-declared AddBlockedByInput / RemoveBlockedByInput
and resolved issue numbers to node IDs with a custom aliased query.

go-github v89 adds first-class REST methods (ListBlockedBy, ListBlocking,
AddBlockedBy, RemoveBlockedBy), so switch issue_dependency_read and
issue_dependency_write to those. This removes the workaround, aligns the
tools with the rest of the REST-based issue tooling, and simplifies tests.

- Rewrite issue_dependencies.go on REST: page-based pagination for reads,
  and a single Issues.Get to resolve the blocking issue's database ID for
  writes. Preserve the tool surface, self-dependency guard and cross-repo
  support.
- Rewrite the issue dependency tests on the REST mock helpers.
- Regenerate the read toolsnap (cursor -> page pagination) and docs.

Refs #950

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

* Normalize issue dependency ref state to match other tools

The REST issue-dependency endpoints return lower-case issue states
(open/closed), whereas the previous GraphQL implementation and the
sibling get_parent tool populate MinimalIssueRef.State from the GraphQL
IssueState enum (OPEN/CLOSED). Upper-case the state in
issueToDependencyRef so the field stays consistent across every tool that
emits a MinimalIssueRef, and guard against a nil issue while here.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: tommaso-moro

docs/feature-flags.md

@@ -310,14 +310,14 @@ runtime behavior (such as output formatting) won't appear here.
 
 - **issue_dependency_read** - Read issue dependencies
   - **Required OAuth Scopes**: `repo`
-  - `after`: Cursor for pagination. Use the cursor from the previous response. (string, optional)
   - `issue_number`: The number of the issue (number, required)
   - `method`: The read operation to perform on a single issue's dependencies.
     Options are:
     1. get_blocked_by - List the issues that block this issue (this issue is blocked by them).
     2. get_blocking - List the issues that this issue blocks.
      (string, required)
   - `owner`: The owner of the repository (string, required)
+  - `page`: Page number for pagination (min 1) (number, optional)
   - `perPage`: Results per page for pagination (min 1, max 100) (number, optional)
   - `repo`: The name of the repository (string, required)
 

docs/insiders-features.md

@@ -105,14 +105,14 @@ The list below is generated from the Go source. It covers tool **inventory and s
 
 - **issue_dependency_read** - Read issue dependencies
   - **Required OAuth Scopes**: `repo`
-  - `after`: Cursor for pagination. Use the cursor from the previous response. (string, optional)
   - `issue_number`: The number of the issue (number, required)
   - `method`: The read operation to perform on a single issue's dependencies.
     Options are:
     1. get_blocked_by - List the issues that block this issue (this issue is blocked by them).
     2. get_blocking - List the issues that this issue blocks.
      (string, required)
   - `owner`: The owner of the repository (string, required)
+  - `page`: Page number for pagination (min 1) (number, optional)
   - `perPage`: Results per page for pagination (min 1, max 100) (number, optional)
   - `repo`: The name of the repository (string, required)
 

pkg/github/__toolsnaps__/issue_dependency_read_ff_issue_dependencies.snap

@@ -7,10 +7,6 @@
   "description": "Read an issue's dependency relationships in a GitHub repository: the issues that block it (blocked_by) or the issues it blocks (blocking).",
   "inputSchema": {
     "properties": {
-      "after": {
-        "description": "Cursor for pagination. Use the cursor from the previous response.",
-        "type": "string"
-      },
       "issue_number": {
         "description": "The number of the issue",
         "type": "number"
@@ -27,6 +23,11 @@
         "description": "The owner of the repository",
         "type": "string"
       },
+      "page": {
+        "description": "Page number for pagination (min 1)",
+        "minimum": 1,
+        "type": "number"
+      },
       "perPage": {
         "description": "Results per page for pagination (min 1, max 100)",
         "maximum": 100,