Make the home page's AS name search work (closes #151)

The AS Name Search card on the home page said the search was coming
soon. It now asks the new GET /api/v1/search/as?q=<text>, which
searches the AS list built into asinfo, and lists the matches as links
to their AS pages. An empty q answers 400. asinfo.Search now ignores
case and returns its matches in AS number order.

A match can be an AS that the database does not hold yet. Its AS page
and /api/v1/as/{asn} now answer with its handle and description from
asinfo and no prefixes, instead of 404. Empty prefix lists in that JSON
answer are [] rather than null.

Model: opus-5-5

README.md

@@ -56,15 +56,16 @@ Every route answers `HEAD` as it answers `GET`, without the body.
 
 ### Web Interface
 
-- `GET /` - Home page (HTML): headline figures, and lookups by AS number and by
-  IP address
+- `GET /` - Home page (HTML): headline figures, lookups by AS number and by IP
+  address, and a search of AS names
 - `GET /status` - HTML status dashboard, which reads `/api/v1/stats`
 - `GET /status.json` - JSON statistics: feed, memory, database and route figures
 - `GET /.well-known/healthcheck.json` - Health check (JSON): 200 when the
   database answers and the RIS Live feed is connected, otherwise 503;
   `data.status` is `ok` or `error` and `data.checks` says which check failed
 - `GET /as/{asn}` - AS detail page (HTML): the prefixes the AS originates and
-  its peers
+  its peers. An AS that only the AS list built into RouteWatch knows gets a page
+  with its handle and description and no prefixes.
 - `GET /prefix/{prefix}/{length}` - Prefix detail page (HTML), such as
   `/prefix/192.0.2.0/24`: every live route for the prefix, one per peer, and its
   origin ASes
@@ -93,9 +94,22 @@ Every route answers `HEAD` as it answers `GET`, without the body.
   and 404 when none of the addresses has a live route. A PTR lookup gets 2
   seconds; an address whose lookup takes longer is answered without PTR names.
 - `GET /api/v1/as/{asn}` - The AS and the prefixes it originates, IPv4 and IPv6
-  apart, each with when its newest route was updated
+  apart, each with when its newest route was updated. An AS that only the AS
+  list built into RouteWatch knows has its handle and description and no
+  prefixes. Its answer has no `first_seen` or `last_seen`.
 - `GET /api/v1/prefix/{prefix}/{length}` - Every live route for the prefix, one
   per peer, and the same routes grouped by origin AS in `origins`
+- `GET /api/v1/search/as?q={text}` - Finds the ASes whose handle or description
+  contains `{text}`, ignoring case. `data` holds:
+    - `query`: `{text}` without its leading and trailing spaces
+    - `total`: the number of ASes that match
+    - `results`: the first 50 of them in AS number order, each with `asn`,
+      `handle` and `description`
+
+    The search reads the AS list built into RouteWatch, not the database. The
+    list comes from [ipverse/asn-info](https://github.com/ipverse/asn-info). A
+    match can therefore be an AS that the database does not hold. A `q` that is
+    missing, empty or only spaces answers 400.
 
 A JSON answer is `{"status": "ok", "data": ...}`, or for an error
 `{"status": "error", "error": {"msg": ..., "code": ...}}`, and carries an
@@ -106,12 +120,13 @@ took. The health check is the exception: its 503 answer is also
 A request that runs past its time limit answers 504: the limit is 30 seconds,
 and 4 seconds for the database reads behind `/status.json` and `/api/v1/stats`.
 An AS number, prefix or mask length that does not parse answers 400, as does a
-mask length out of range for its IP version. An AS the database does not hold,
-or a prefix with no live route, answers 404. The HTML pages give these errors as
-plain text. Under `/api/v1` and `/ip/`, a path no route matches answers 404 with
-the message `Not found`, and `POST`, `PUT`, `PATCH`, `DELETE`, `OPTIONS`,
-`TRACE` or `CONNECT` answers 405 with `Method not allowed`. A 500 answer says
-only `Internal server error`, and a host name that does not resolve only
+mask length out of range for its IP version. An AS number that is in neither the
+database nor the AS list built into RouteWatch answers 404, as does a prefix
+with no live route. The HTML pages give these errors as plain text. Under
+`/api/v1` and `/ip/`, a path no route matches answers 404 with the message
+`Not found`, and `POST`, `PUT`, `PATCH`, `DELETE`, `OPTIONS`, `TRACE` or
+`CONNECT` answers 405 with `Method not allowed`. A 500 answer says only
+`Internal server error`, and a host name that does not resolve only
 `could not resolve host name`; the detail goes to the log.
 
 Every answer carries `Strict-Transport-Security`, `Content-Security-Policy`,