Remove the CrowdSec decision feed (closes #315)

sneak ruled to remove it. Gone: the heuristic crowdsec, the ban cause
crowdsec and its earlier_bans count, the tag crowdsec, the settings
SWW_WAF_CROWDSEC_LAPI_URL and SWW_WAF_CROWDSEC_LAPI_KEY, the decision
list fetch and parse in internal/reputation, their tests, and every
mention in the README, SPEC.md and docs/. EVALUATION.md keeps its
comparison of tools.

The ban ledger's internal ban function loses its expires parameter,
which only CrowdSec bans used.

Model: opus-5-5

docs/state-files.md

@@ -25,7 +25,7 @@ Active and past bans: every ban an admin made, and up to `SWW_WAF_MAX_BANS` of
 those `waf` made. Per entry:
 
 - `netblock`, `start` and `expires` (`null` for a permanent ban);
-- `cause`: `attack`, `limit`, `admin` or `crowdsec`;
+- `cause`: `attack`, `limit` or `admin`;
 - `reason`: a short reason;
 - `lifted`: when an admin lifted it, if one did;
 - `notes`: the notes below.