Add 'Set Recap License' StartOS action + s/Keysat license/Recap license/

Two related changes:

1. New StartOS action: 'Set Recap License'

   Symmetric with the existing 'Set Gemini API Key' action — paste a
   LIC1-... key into the StartOS Actions menu and it gets persisted.
   Added because some users prefer the StartOS form for credentials
   over the in-app activation modal.

   Implementation:
     • startos/file-models/config.json.ts: schema gains recap_license_key
     • startos/actions/setLicense.ts: input form (masked, regex-checks
       for the LIC1- prefix), persists via configFile.merge()
     • startos/actions/index.ts: registers the new action
     • server/license.js: readLicenseString() falls back to
       startos-config.json after the legacy license.txt path. Resolution
       order: env → license.txt → startos-config.json
     • server/license-middleware.js: faster license-file poll (30 s,
       env-overridable RECAP_LICENSE_FILE_POLL_MS) re-runs checkLicense
       so action-set keys take effect within seconds, not the 6 h online
       cycle. If the new key parses as 'licensed', kicks an immediate
       online check to confirm.

2. Copy fix: 'Keysat license' → 'Recap license' in user-facing text

   Keysat is the licensing system underneath, but customers buy a
   'Recap license'. Updated:
     • Activation screen subtitle (public/index.html)
     • 402 message in the activation gate (server/license-middleware.js)

   Internal references (PRODUCT_SLUG, KEYSAT_BASE_URL, the issuer.pub
   filename, the 'Issuer: licensing.keysat.xyz' display in the
   activation card) stay as Keysat — those are accurate.

Smoke tested locally: starting the server with no license, then
writing a fake LIC1-... key into startos-config.json, the
license-file poll picks it up within ~2 s and transitions state from
'unlicensed' to 'invalid' (since the fake key fails Ed25519
verification, as expected). With a real key, the same path would land
in 'licensed'.

startos/file-models/config.json.ts

@@ -11,5 +11,6 @@ export const configFile = FileHelper.json(
   },
   z.object({
     gemini_api_key: z.string().default(''),
+    recap_license_key: z.string().default(''),
   }),
 )