Assessment Pipeline: Add L1 (Eliminatory) filters, post-processing & results view

[vprashrex]

Is your feature request related to a problem?
The current assessment flow only allows for a single LLM pass, leading to irrelevant rows hitting the model and requiring manual processing after results are exported. This results in wasted cost and inefficient workflow.

Describe the solution you'd like
Enhance the assessment pipeline with:

• An Eliminatory (L1) pre-filter stage:
  • Topic Relevance — exclude REJECT rows.
  • Duplicate Detection — report checks in the export.
• A Post Processing stage for computed columns, filtering, and sorting, usable before and after the run.
• A dedicated full-page view for results instead of a cramped modal.
• Display L1 pass/reject stats and the latest model per saved config.

Original issue

Describe the current behavior
The assessment flow only supported a single LLM pass (prompt + config → results).
There was no way to:

• Pre-filter rows before the expensive LLM batch (e.g. drop off-topic or duplicate
  submissions), so every row hit the model regardless of relevance.
• Post-process results (derive scores, filter, sort) without exporting to a
  spreadsheet and doing it by hand.
• View results comfortably — the preview opened in a cramped modal.

For high-volume datasets this means wasted LLM cost on irrelevant rows and manual
spreadsheet work after every run.

Describe the enhancement you'd like

• Add an Eliminatory (L1) pre-filter stage before evaluation:
  • Topic Relevance — gate that excludes REJECT rows from evaluation.
  • Duplicate Detection — passthrough check reported in the export.
• Add a Post Processing stage (computed columns, filter, sort) usable both
  before the run and on completed runs.
• Open results in a dedicated full-page spreadsheet view instead of a modal.
• Surface L1 pass/reject stats and the latest model per saved config.