Normalize trailing slashes in page URLs

[yosriady]

Motivation

• Analytics page URLs and page properties should be canonicalized so that routes with and without trailing slashes are deduplicated for reporting and dropdowns.
• Trailing-slash normalization should not change the root / and must preserve query strings and hash fragments.

Description

• Add a private normalizeUrlPath(url: URL) helper to strip trailing slashes from non-root pathnames and call it from redactUrl and the page-properties parsing path in getPageProperties (file src/event/EventFactory.ts).
• Apply normalization when building the context page_url (via redactUrl) and when populating page properties so url/path reflect the normalized path while preserving ?query and #hash.
• Use the parsed URL (urlObj.pathname) for pageProps.path instead of globalThis.location.pathname so the normalized pathname is used when available.
• Add tests in test/lib/event/PagePropertiesParsing.spec.ts that assert non-root trailing-slash stripping (/limit/bnb/ → /limit/bnb) and root-path preservation (/ remains /).

Testing

• Ran lint with pnpm lint and it completed successfully.
• Ran the page properties tests with pnpm test -- test/lib/event/PagePropertiesParsing.spec.ts and the tests (including the two new assertions) passed as part of the full suite (651 passing).

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Codex Task

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