feat(p10-3): code-text-paragraph-v1 chunker — paragraph + line-window fallback

Blank-line paragraph segmentation (whitespace-only lines as boundaries,
blank lines themselves never in any chunk's range). Paragraphs > 80 lines
split into 80-line windows with 20-line overlap (stride 60), sharing the
input lang and symbol=None per spec §9.3. tier2_shared exposes a new
build_chunk_no_symbol helper so Chunk id/hash/token semantics stay
identical with Tier 1/2. Extracts build_chunk_from_span as private core
so build_chunk and build_chunk_no_symbol share mechanics without drift.

4 unit tests cover multi-paragraph shell (4 paragraphs, blank-line
boundaries verified), 200-line oversize line-window split (chunks
1-80 / 61-140 / 121-200), empty file, and lang preservation when
input is yaml.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/kebab-chunk/tests/fixtures/sample_shell.sh

@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# First paragraph: env setup
+export KEBAB_HOME="${KEBAB_HOME:-$HOME/.local/share/kebab}"
+mkdir -p "$KEBAB_HOME"
+cd "$KEBAB_HOME"
+
+# Second paragraph: ingest
+echo "ingesting workspace..."
+kebab ingest --config /etc/kebab/config.toml
+
+# Third paragraph: report
+echo "done"
+kebab schema --json | jq '.stats'