Fix code-mode navigation of filedef links

[lukemelia]

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[Copilot]

Pull request overview

This PR fixes navigation of FileDef links in code mode by preventing automatic extension fallbacks for files that already have non-executable extensions. Previously, requests for files like .md would incorrectly attempt to add executable extensions or redirect.

Changes:

• Added hasExtension() utility function to detect if a path contains a file extension
• Modified realm file handling to skip extension fallbacks for non-executable files with extensions
• Updated code mode navigation to use hasExtension() instead of checking only for .json extension

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/runtime-common/url.ts	Adds hasExtension() helper to detect file extensions in URLs or paths
packages/runtime-common/realm.ts	Updates file request handling to avoid fallback extensions for non-executable files that already have extensions
packages/realm-server/tests/card-source-endpoints-test.ts	Adds test verifying non-executable files (e.g., .md) are served without redirect
packages/host/tests/acceptance/code-submode/file-def-navigation-test.gts	Adds acceptance test for navigating to markdown files via FileDef links in code mode
packages/host/app/components/operator-mode/code-submode/module-inspector.gts	Updates card navigation to use hasExtension() for broader file type support

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Host Test Results

    1 files  ±  0      1 suites  ±0   1h 38m 7s ⏱️ + 9m 20s
1 894 tests +213  1 877 ✅ +215  17 💤 ±0  0 ❌  - 1 
1 909 runs  +214  1 892 ✅ +217  17 💤 ±0  0 ❌  - 2 

Results for commit 8397b84. ± Comparison against base commit 743df5f.

This pull request removes 1 and adds 214 tests. Note that renamed tests count towards both.

Chrome ‑ Global error: Uncaught TypeError: Failed to fetch at http://localhost:7357/assets/chunk.9c8e4eccabdfee0d9873.js, line 150984  While executing test: Integration | card-copy: copy button does not appear when right and left stacks are the same index item and there is a selection on one side 

Chrome ‑ Acceptance | code submode | file def navigation: clicking embedded file in preview opens markdown file in code mode
Chrome ‑ Integration | Store: added instance that was previously not saved will begin to auto save after being added
Chrome ‑ Integration | Store: an instance can be restored after a loader reset
Chrome ‑ Integration | Store: an instance can debounce auto saves
Chrome ‑ Integration | Store: an instance can live update thru an error state
Chrome ‑ Integration | Store: an instance live updates from indexing events for a code update
Chrome ‑ Integration | Store: an instance live updates from indexing events for an instance update
Chrome ‑ Integration | Store: an instance that started out with a local ID can be restored after a loader reset
Chrome ‑ Integration | Store: an instance will NOT auto save when its data changes, if the user does not have write permissions
Chrome ‑ Integration | Store: an instance will auto save when its data changes
…

♻️ This comment has been updated with latest results.