fix: Sanitize index names to support CouchDB > 3.3.3

[Crash--]

I didn't find a commit from CouchDB relative to this issue, but it's somewhere between 3.3.3 & 3.5.1.

Partial filter values containing "/" (e.g. "/Settings") produced index names incompatible with new CouchDB. Percent-encode "/" as "%2F" (and "%" as "%25") to avoid naming issues while preserving uniqueness.

Closes #1667

Summary by CodeRabbit

• Bug Fixes

  • Index name generation now encodes special characters (forward slashes and percent signs) for filtered queries, preventing invalid names and ensuring consistent query behavior.

• Tests

  • Added tests verifying proper encoding of special characters in index names and that distinct indexes are produced when filter values differ.

[coderabbitai]

Walkthrough

The change adds a private helper sanitizeIndexName in two packages (cozy-pouch-link and cozy-stack-client) that percent-encodes % as %25 and / as %2F. getIndexNameFromFields is updated in both packages to apply this sanitization when a partialFilter is present. Tests were added to verify slash encoding and that index names differ when partial filter values contain a slash. No public API signatures were changed.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely identifies the main change: sanitizing index names to support newer CouchDB versions, directly addressing the core fix in the PR.
Linked Issues check	✅ Passed	The PR fully satisfies issue #1667 by implementing percent-encoding of '/' as '%2F' and '%' as '%25' in index names, with test coverage validating the sanitization behavior.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to implementing and testing index name sanitization; no unrelated modifications are present.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix/sanitize-index-name

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@packages/cozy-stack-client/src/mangoIndex.spec.js`:
- Around line 258-274: The test's partialFilter defines a $nin array spread
across multiple lines which trips Prettier; update the test "should sanitize
slash characters from index name" so the $nin arrays (both for _id and for
path.$or[1].$nin) are formatted on a single line (e.g. ['$a','/Settings'] style)
to satisfy Prettier, keeping the same values and leaving the rest of the test
and the call to getIndexNameFromFields unchanged.

🧹 Nitpick comments (1)

packages/cozy-stack-client/src/mangoIndex.js (1)

108-118: Consider extracting sanitizeIndexName to a shared utility.

This function is duplicated verbatim in packages/cozy-pouch-link/src/mango.js. While the existing "Warning" comments remind developers to keep them in sync, a shared module would eliminate the risk of divergence. Low priority given the existing convention in this codebase.