Route validation matching by Census layer (#120)

[frankcampos]

Closes #120. Follow-up to #119.

The problem

find_matches() hard-filtered every candidate to the Census place layer, so the county and state rows that #119 loaded could never be reached. A county: or state-only OCDid returned an empty frame and was quarantined as a stub.

The change

Route by the OCDid's deepest segment. The layer column carries the TIGER file stem the row came from, so its suffix names the layer:

OCDid	layer suffix	matched against
place:seattle	_place	seattle
county:king	_county	king
bare state:wa	_state	washington

• _filter_to_place_layer becomes _filter_to_layer(df, layer). It keeps the old PLACEFP heuristic as a fallback for a CSV with no layer column.
• A state-only OCDid matches on the state's full name from state_lookup, because the States tab carries Washington in NAMELSAD, not wa.
• territory: now falls back alongside district:, so Puerto Rico and Guam resolve against their States-tab rows. This is one line beyond the ticket, but generate_ocdids() emits those ids and the sheet has the rows.

Naming fix in generate_division

Every council district in a county matches that one county row, so all of them took the county's display name and collided on the {display_name}_{geoid} filename — ten Blount County districts all wrote to blount_47009_*.yaml, separated only by a UUID.

_county_council_district_display_name builds the name from the record's NAMELSAD rather than the OCDid slug. Using NAMELSAD instead of appending the literal word "County" keeps Louisiana parishes and Alaska boroughs correct:

county:blount/council_district:10   ->  Blount County Council District 10
county:orleans/council_district:2   ->  Orleans Parish Council District 2

Verification

pipeline summary

# all tests passed

Replayed the Tennessee set (829 records) against the live sheets, then ran the real pipeline end to end:

	before	after
success	36	829
partial (quarantined stub)	793	0

Every record resolves to exactly one row. Nothing lands in the 0 or 2+ branch. Spot checks: state:wa → Washington (tl_2025_us_state), state:tn/county:davidson → Davidson County (tl_2025_47_county), territory:pr → Puerto Rico, state:wa/place:seattle → Seattle city.

173 tests pass. ruff check and ruff format --check are clean.

Tests added

Five integration cases in test_generate_pipeline_integration.py — one state, one county, and three cross-layer isolation cases — plus two decoy fixture rows (King city, Washington city) so a name-only match would visibly cross layers. Four unit cases in test_generate_division.py cover the county display name, including the parish case.