fix(utils): make normalizePath idempotent by globally collapsing repeated slashes (#161)

[deus-intus]

Fixes #161

Problem

On main, normalizePath only collapsed the first repeated slash group because the regex lacked the global (g) flag:

• normalizePath("a///b///c.txt") returned "a/b///c.txt" instead of "a/b/c.txt".
• normalizePath("a//b//c//d") returned "a/b//c//d" instead of "a/b/c/d".
• Applying normalizePath multiple times changed the result, causing non-idempotent behavior during database storage and lookups.

Solution

Added the global /g flag to the slash collapse regex in lib/utils/normalize-path.ts:

- let normalized = path.replace(/\\+/g, "/").replace(/\/\/+/, "/")
+ let normalized = path.replace(/\\+/g, "/").replace(/\/\/+/g, "/")

Verification

Added tests/normalize-path.test.ts verifying:

1. Multiple repeated slash groups collapse cleanly.
2. Idempotence across multiple passes over the same string.
3. Mixed backslashes and Windows separators normalize properly.
4. Empty string and root path edge cases.

Ran full test suite with Bun (bun test): all 33 tests across 10 files pass cleanly.