fix: share-link first visit doesn't open anchor modal (#470)

[raifdmueller]

Closes #470

Summary

When opening a share-link like `/#/anchor/` in a fresh tab, the homepage was rendered instead of the anchor modal. On a second visit the modal already existed and the link worked — making the bug look intermittent.

Root cause

`router.handleRoute()` invoked `showAnchorDetails()` before `initApp`'s `createModal()` microtask ran. `loadAnchorContent()` then crashed inside the dynamic-import callback with:

```
TypeError: Cannot read properties of null (reading 'querySelector')
at loadAnchorContent (anchor-modal.js:164)
```

The modal element didn't exist yet, the URL got rewritten to `/anchor/...` by the SPA's hash→path migration, the title was set correctly, but no modal opened.

Fix

Guard `showAnchorDetails()` by calling the idempotent `createModal()` when the element is missing. Cheap, defensive, no behavioral change on the happy path.

Test plan

• Regression test added: `anchor-modal.test.js` — removes the modal element, calls `showAnchorDetails`, asserts it doesn't throw, the modal is created, and the `hidden` class is removed
• Full unit test suite passes (90/90)
• Production build verified with Playwright against `http://localhost:4173/Semantic-Anchors/#/anchor/plain-english-strunk-white\`:
  • Modal opens (`display: flex`)
  • Title rendered: "Plain English according to Strunk & White"
  • Content loaded (2185 chars)
  • Zero console errors

🤖 Generated with Claude Code

Summary by CodeRabbit

Bug Fixes

• Behoben: Das Anker-Detailfenster wird nun zuverlässig angezeigt, auch wenn es unter bestimmten Bedingungen aufgerufen wird.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yml

Review profile: CHILL

Plan: Pro

Run ID: 92aa47e9-e699-4eee-aae2-c287c6aab028

📥 Commits

Reviewing files that changed from the base of the PR and between 5e35499 and e8f7d67.

📒 Files selected for processing (3)

• .gitignore
• website/src/components/anchor-modal.js
• website/src/components/anchor-modal.test.js

---

Walkthrough

Das Pull Request behebt eine Racebedingung bei Anker-Freigabelinks, die beim ersten Besuch dazu führt, dass das Modal nicht geöffnet wird. Die Funktion showAnchorDetails erstellt nun bei Bedarf das Modal-Element und wird durch einen Testfall validiert, der dieses Szenario reproduziert. Zusätzlich werden Gitignore-Einträge für lokale Verzeichnisse hinzugefügt.

Changes

Behebung der Racebedingung bei Anker-Modalen

Layer / Datei(en)	Zusammenfassung
Modal-Initialisierungsicherung und Race-Condition-Handling website/src/components/anchor-modal.js, website/src/components/anchor-modal.test.js	showAnchorDetails verwendet nun ein Fallback createModal(), wenn #anchor-modal noch nicht vorhanden ist. Ein neuer Testfall validiert dieses Szenario, indem das Modal entfernt wird, die Funktion aufgerufen wird und anschließend überprüft wird, dass das Modal neu erstellt und sichtbar ist.
Entwicklungsumgebungs-Konfiguration .gitignore	Gitignore wird um Einträge für .venv/ und .linkedin/ erweitert, um lokale Verzeichnisse von der Versionskontrolle auszuschließen.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main fix: resolving the race condition where share-links to anchors fail to open the modal on first visit.
Linked Issues check	✅ Passed	All code changes directly address issue #470: showAnchorDetails() now guards against missing modal elements by calling createModal(), preventing the TypeError and ensuring the modal opens reliably.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to fixing the share-link race condition: .gitignore additions are project housekeeping, anchor-modal.js implements the race-condition fix, and tests verify the solution.

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