feat(gitsync): enrich PR status with author, base branch, review info (#23038)

## Summary

Adds 7 new fields to the PR status stored by gitsync, all sourced from
the existing GitHub API calls (**zero additional HTTP requests**):

| Field | Source | Purpose |
|---|---|---|
| `author_login` | `pull.user.login` | PR author username |
| `author_avatar_url` | `pull.user.avatar_url` | PR author avatar for UI
|
| `base_branch` | `pull.base.ref` | Target branch (e.g. `main`) |
| `pr_number` | `pull.number` | Explicit PR number |
| `commits` | `pull.commits` | Number of commits in PR |
| `approved` | Derived from reviews | True when ≥1 approved, no
outstanding changes requested |
| `reviewer_count` | Derived from reviews | Distinct reviewers with a
decisive state |

## Changes

- **`gitprovider/gitprovider.go`**: Added 7 fields to `PRStatus` struct.
- **`gitprovider/github.go`**: Expanded the anonymous struct in
`FetchPullRequestStatus` to decode new JSON fields. Replaced
`hasOutstandingChangesRequested()` with `summarizeReviews()` returning a
`reviewStats` struct with `changesRequested`, `approved`, and
`reviewerCount`.
- **Migration 000434**: Adds 7 columns to `chat_diff_statuses`.
- **`queries/chats.sql`**: Updated `UpsertChatDiffStatus`
INSERT/VALUES/ON CONFLICT.
- **`gitsync/gitsync.go`**: Maps new `PRStatus` fields into upsert
params.
- **`gitsync/worker.go`**: Maps new columns in row-to-model converter.
- **`codersdk/chats.go`**: Added fields to SDK `ChatDiffStatus` type.
- **`coderd/chats.go`**: Maps new DB fields in
`convertChatDiffStatus()`.
- Auto-generated: `models.go`, `queries.sql.go`, `dump.sql`,
`typesGenerated.ts`.

coderd/externalauth/gitprovider/github.go

@@ -265,9 +265,18 @@ func (g *githubProvider) FetchPullRequestStatus(
 		Additions    int32  `json:"additions"`
 		Deletions    int32  `json:"deletions"`
 		ChangedFiles int32  `json:"changed_files"`
+		Number       int    `json:"number"`
+		Commits      int32  `json:"commits"`
 		Head         struct {
 			SHA string `json:"sha"`
 		} `json:"head"`
+		User struct {
+			Login     string `json:"login"`
+			AvatarURL string `json:"avatar_url"`
+		} `json:"user"`
+		Base struct {
+			Ref string `json:"ref"`
+		} `json:"base"`
 	}
 	if err := g.decodeJSON(ctx, pullEndpoint, token, &pull); err != nil {
 		return nil, err
@@ -298,6 +307,8 @@ func (g *githubProvider) FetchPullRequestStatus(
 		state = PRStateMerged
 	}
 
+	reviewInfo := summarizeReviews(reviews)
+
 	return &PRStatus{
 		Title:   pull.Title,
 		State:   state,
@@ -308,7 +319,14 @@ func (g *githubProvider) FetchPullRequestStatus(
 			Deletions:    pull.Deletions,
 			ChangedFiles: pull.ChangedFiles,
 		},
-		ChangesRequested: hasOutstandingChangesRequested(reviews),
+		ChangesRequested: reviewInfo.changesRequested,
+		Approved:         reviewInfo.approved,
+		ReviewerCount:    reviewInfo.reviewerCount,
+		AuthorLogin:      pull.User.Login,
+		AuthorAvatarURL:  pull.User.AvatarURL,
+		BaseBranch:       pull.Base.Ref,
+		PRNumber:         pull.Number,
+		Commits:          pull.Commits,
 		FetchedAt:        g.clock.Now().UTC(),
 	}, nil
 }
@@ -495,7 +513,18 @@ func ParseRetryAfter(h http.Header, clk quartz.Clock) time.Duration {
 	return 0
 }
 
-func hasOutstandingChangesRequested(
+// reviewStats holds aggregated review statistics for a PR.
+type reviewStats struct {
+	changesRequested bool
+	approved         bool
+	reviewerCount    int32
+}
+
+// summarizeReviews extracts review statistics from a list of
+// reviews. For each reviewer, only the latest decisive review
+// (by ID) is considered. "Decisive" means APPROVED,
+// CHANGES_REQUESTED, or DISMISSED.
+func summarizeReviews(
 	reviews []struct {
 		ID    int64  `json:"id"`
 		State string `json:"state"`
@@ -503,7 +532,7 @@ func hasOutstandingChangesRequested(
 			Login string `json:"login"`
 		} `json:"user"`
 	},
-) bool {
+) reviewStats {
 	type reviewerState struct {
 		reviewID int64
 		state    string
@@ -533,10 +562,21 @@ func hasOutstandingChangesRequested(
 		}
 	}
 
+	var result reviewStats
+	result.reviewerCount = int32(len(statesByReviewer))
+
+	hasApproval := false
 	for _, state := range statesByReviewer {
 		if state.state == "CHANGES_REQUESTED" {
-			return true
+			result.changesRequested = true
+		}
+		if state.state == "APPROVED" {
+			hasApproval = true
 		}
 	}
-	return false
+	// Approved is true only when at least one reviewer approved
+	// and no reviewer has outstanding changes requested.
+	result.approved = hasApproval && !result.changesRequested
+
+	return result
 }

coderd/externalauth/gitprovider/gitprovider.go

@@ -79,6 +79,23 @@ type PRStatus struct {
 	// ChangesRequested is a convenience boolean: true if any
 	// reviewer's current state is "changes_requested".
 	ChangesRequested bool
+	// AuthorLogin is the login/username of the PR author.
+	AuthorLogin string
+	// AuthorAvatarURL is the avatar URL of the PR author.
+	AuthorAvatarURL string
+	// BaseBranch is the target branch the PR will merge into.
+	BaseBranch string
+	// PRNumber is the PR number (e.g. 1347).
+	PRNumber int
+	// Commits is the number of commits in the PR.
+	Commits int32
+	// Approved is true when at least one reviewer has approved
+	// and no reviewer has outstanding changes requested.
+	Approved bool
+	// ReviewerCount is the number of distinct reviewers who
+	// have left a decisive review (approved, changes_requested,
+	// or dismissed).
+	ReviewerCount int32
 	// FetchedAt is when this status was fetched.
 	FetchedAt time.Time
 }