* 🐛 fix: Enforce fileLimit and totalSizeLimit in Attached Files panel
The Files side panel (PanelTable) was not checking fileLimit or
totalSizeLimit from fileConfig when attaching previously uploaded files,
allowing users to bypass per-endpoint file count and total size limits.
* 🔧 fix: Address review findings on file limit enforcement
- Fix totalSizeLimit double-counting size of already-attached files
- Clarify fileLimit error message: "File limit reached: N files (endpoint)"
- Replace Array.from(...).reduce with for...of loop to avoid intermediate allocation
- Extract inline `type TFile` into standalone `import type` per project conventions
* ✅ test: Add PanelTable handleFileClick file limit tests
Cover fileLimit guard, totalSizeLimit guard, passing case,
double-count prevention for re-attached files, and boundary case.
* 🔧 test: Harden PanelTable test mock setup
- Use explicit endpoint key matching mockConversation.endpoint
instead of relying on default fallback behavior
- Add supportedMimeTypes to mock config for explicit MIME coverage
- Throw on missing filename cell in clickFilenameCell to prevent
silent false-positive blocking assertions
* ♻️ refactor: Align file validation ordering and messaging across upload paths
- Reorder handleFileClick checks to match validateFiles:
disabled → fileLimit → fileSizeLimit → checkType → totalSizeLimit
- Change fileSizeLimit comparison from > to >= in handleFileClick
to match validateFiles behavior
- Align validateFiles error strings with localized key wording:
"File limit reached:", "File size limit exceeded:", etc.
- Remove stray console.log in validateFiles MIME-type check
* ✅ test: Add validateFiles unit tests for both paths' consistency
13 tests covering disabled, empty, fileLimit (reject + boundary),
fileSizeLimit (>= at limit + under limit), checkType, totalSizeLimit
(reject + at limit), duplicate detection, and check ordering.
Ensures both validateFiles and handleFileClick enforce the same
validation rules in the same order.
