Improve webhook setup error messages and auto-show manual instructions on failure

[JohnRDOrazio]

Problem

When enabling webhooks in project settings, error handling discards backend diagnostic information and shows only generic messages. When the enable-webhook request or auto-setup fails, manual webhook setup instructions are not shown at all.

Current Behavior

There are two failure scenarios, both with UX problems:

Scenario A — The PATCH to toggle webhooks_enabled itself fails (line 2096 catch):
This is the scenario triggered by the "Failed to update webhook settings" error. The state flow:

1. githubIntegrationApi.update() throws
2. Outer catch fires → setError("Failed to update webhook settings")
3. onIntegrationUpdate was never called → githubIntegration.webhooks_enabled stays false
4. The entire webhook content section gated by {githubIntegration.webhooks_enabled && ( at line 2150 does not render
5. showManualSetup is false (line 2124 requires webhooks_enabled to be true)
6. The setTimeout auto-setup never runs — we hit the catch before reaching it
7. Result: user sees only "Failed to update webhook settings" with no manual setup option and no way forward

Scenario B — The PATCH succeeds but setupWebhook auto-setup fails (line 2090 catch):

1. githubIntegrationApi.update() succeeds → webhooks_enabled = true
2. setTimeout fires → setupWebhook() throws
3. Catch sets webhookStatus = "unknown" with no error message
4. showManualSetup is true, "Show manual setup details" button renders
5. But there is no visual indication that something failed — no error, no warning badge
6. Result: user sees the toggle as enabled but gets no feedback about the failure, must discover the setup button on their own

Error Information Available but Discarded

The ApiError class carries the full backend response in message (parsed from response.text() at client.ts:57-58). The backend returns JSON like {"detail": "GitHub token lacks 'admin:repo_hook' scope"}. All three catch blocks discard this:

Catch block	Line	Current message	Backend detail discarded
handleToggleWebhooks	2096	"Failed to update webhook settings"	Yes
Auto-setup after toggle	2090	(no message at all)	Yes
runWebhookSetup retry	2052	"Failed to setup webhook."	Yes

Proposed Fix

1. Extract and display backend error details

In all three catch blocks, extract the detail from ApiError:

} catch (err) {
  let detail = "Failed to update webhook settings";
  if (err instanceof ApiError) {
    try {
      const body = JSON.parse(err.message);
      detail = body.detail || err.message;
    } catch {
      detail = err.message || detail;
    }
  }
  setError(detail);
}

2. Add expandable error detail UI

Replace the plain error <p> with a collapsible detail:

⚠ Failed to update webhook settings  [Show details ▾]
   └─ "GitHub App token does not have 'admin:repo_hook' scope. 
       Use manual webhook setup instead."

This could be a simple <details>/<summary> element or a "Show details" toggle.

3. Show manual setup when the PATCH fails (Scenario A)

When the update() PATCH fails, the manual setup section is completely hidden because webhooks_enabled remains false. The fix should show manual setup instructions alongside the error even when the toggle PATCH failed:

• Either: decouple the manual setup UI from webhooks_enabled — show it whenever there's a webhook-related error
• Or: add a "Set up webhook manually instead" link/button next to the error message that reveals the manual setup section regardless of toggle state

4. Auto-reveal manual setup on auto-setup failure (Scenario B)

When the auto-setup catch fires (line 2090-2092), set webhookStatus to "error" (not "unknown") so that:

• The retry button is visible (webhookStatus !== "unknown" is true)
• An error message is shown (currently none)
• Ideally also trigger handleRevealSecret() to auto-reveal the URL/secret/instructions

5. Show webhook status message for non-success states

The webhookMessage from setupWebhook response includes useful info for no_scope, no_token, and manual_required statuses, but should be visually distinguished for error-like states (e.g. red/amber styling for error/no_scope/no_token).

Affected Code

Location	Line	Issue
handleToggleWebhooks catch	settings/page.tsx:2096	Generic error, discards ApiError.message, no manual setup shown
Auto-setup catch after toggle	settings/page.tsx:2090	Silent failure, no error shown, sets status to "unknown" instead of "error"
runWebhookSetup catch	settings/page.tsx:2052	Generic error, discards ApiError.message
Webhook content gate	settings/page.tsx:2150	Entire section hidden when webhooks_enabled is false
showManualSetup logic	settings/page.tsx:2124	Requires webhooks_enabled to be true — no manual fallback when PATCH fails
Error display	settings/page.tsx:2276	Plain text, no expandable detail, no link to manual setup

Acceptance Criteria

• Backend error detail is extracted and shown (not just generic message)
• Expandable "Show details" for long error messages
• Manual setup instructions accessible even when the enable-webhook PATCH itself fails
• Manual setup (URL, secret, instructions) prominently shown when auto-setup fails
• webhookStatus set to "error" (not "unknown") on auto-setup failure, so retry button and error feedback are visible
• Status-appropriate styling for error/warning webhook states (no_scope, no_token, manual_required)
• Retry button remains visible alongside manual setup instructions