feat: proposal intake pipeline with AI-powered generation on /proposals/new

Add full proposal system: DB schema (proposals + proposal_gaps tables),
CLI `ietf intake` command, and web UI with Quick Generate on /proposals/new.
The new page merges AI intake (paste URL/text → Haiku generates multiple
proposals auto-linked to gaps) with manual form entry. Generated proposals
are clickable cards that fill the editor below for refinement.

Uses claude_model_cheap (Haiku) for cost-efficient web intake. Includes
CaML-inspired draft proposals from arXiv:2503.18813 analysis.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/proposal-intake.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+# Proposal Intake — generate IETF draft proposals from text/URLs.
+#
+# Usage:
+#   ./scripts/proposal-intake.sh "https://arxiv.org/abs/2503.18813"
+#   ./scripts/proposal-intake.sh -f notes.txt
+#   echo "article text" | ./scripts/proposal-intake.sh -
+#   ./scripts/proposal-intake.sh --dry-run "some interesting paper text"
+#
+# This passes input to Claude along with all current gaps,
+# and stores generated proposals in the database.
+# View results at http://localhost:5000/proposals (--dev mode)
+
+set -euo pipefail
+cd "$(dirname "$0")/.."
+
+python -m ietf_analyzer.cli intake "$@"