Zone matrix: partly, what is let through, hits; hc matrix aligned

A cell reads allow, block or partly (some new connections let through,
the rest not), with its exceptions counted by what they do (+3 -1), and
what they let through: services with the addresses they are limited to,
under the grid in hc matrix and in each cell on the Matrix page. A zone
to itself is marked: only traffic routed between its interfaces passes
the firewall. The details list each rule's hits. hc matrix pads the
grid by visible width: the colours' escape codes had thrown it out of
line.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/api.md

@@ -77,7 +77,7 @@ Creating answers 201, other changes 200.
 | `GET /healthz` | `ok`, `version`, `firewall` (`applied`, `unconfigured`, `fallback`, `missing`), `mode` (`enforcing`, or `shadow`: the ruleset blocks nothing, [shadow.md](shadow.md)), `probation` (changes waiting to be confirmed), `warnings` (codes); HTTP 503 unless `ok`. Without authentication; read at most every five seconds ([operations.md](operations.md#monitoring)) |
 | `GET /status` | `build`, `started`, `mode` (`enforcing` or `shadow`), `shadow_position` (`after` or `before`, in shadow mode), `applied` (the ruleset is in force), `apply_error`, `problems`, `probation`, `interfaces`, `counts` (objects by kind), `other_tables` (other nftables tables, `"inet main"`) |
 | `GET /interfaces` | the machine's interfaces: `name`, `up`, `addresses`, `zone` |
-| `GET /matrix[?changeset=ID]` | the zone matrix: `zones`, `cells` (`from`, `to` (a zone, or `firewall`), `chain`, `verdict` (allowed, blocked), `decided_by`, `rule_id`, `exceptions`: `rule_id`, `chain`, `label`, `verdict` (allowed, blocked, logged, unknown), `what`) ([rules.md](rules.md#the-zone-matrix)) |
+| `GET /matrix[?changeset=ID]` | the zone matrix: `zones`, `cells` (`from`, `to` (a zone, or `firewall`), `chain`, `summary` (allowed, blocked, partly), `verdict` (what the rest gets: allowed, blocked), `decided_by`, `rule_id`, `hits`, `allowed` and `blocked` (exceptions by verdict), `open` (what the allowing exceptions let through, in short), `same_zone` and `note`, `exceptions`: `rule_id`, `chain`, `label`, `verdict` (allowed, blocked, logged, unknown), `what`, `short`, `hits`). `hits` are the rule's or policy's packets since housecarld started, all its traffic (missing: no counter) ([rules.md](rules.md#the-zone-matrix)) |
 | `GET /ruleset[?enforcing=1]` | the nftables ruleset Housecarl builds, as text. In shadow mode it is the shadow ruleset; `enforcing=1` gives the one loaded once shadow mode is off |
 | `GET /counters` | `{"since", "counters": {"r12": {"packets", "bytes"}, ...}}`, by mark ([design.md](design.md#its-own-table-only)); totals since housecarld started |
 | `GET /quotas` | each rule's quota: `rule_id`, `rule`, `quota`, `used` (bytes), `addresses` (`[{"address", "used"}]` for a per-address quota), `last_reset`, `next_reset` |