feat: schema inference from network requests (GLA-46)

[paoloanzn]

Summary

• Adds schema-inferrer.js module that extracts typed schemas from a single captured network request, covering both request and response sides
• Header schemas: field name, inferred value type (string, integer, number, boolean, empty), and isAuth flag for auth headers (Authorization, bearer tokens, x-api-key, Cookie, x-auth-*)
• Body schemas: recursive type inference for JSON payloads (string, number, boolean, null, array, object with named fields) and URL-encoded form data with value coercion
• Supports schema unification across array items (mixed type with variants) and optional field tracking for future schema merging (GLA-47)
• Integrates into export payload (schema field per request) and panel UI (new "Inferred Schema" detail section)

Test plan

• Load extension in Chrome DevTools, trigger network requests with JSON request/response bodies
• Verify "Inferred Schema" section appears in request detail view with correct types
• Test with form-urlencoded POST bodies — schema should parse key/value pairs with coerced types
• Test auth header detection: requests with Authorization: Bearer ..., x-api-key, Cookie headers should have isAuth: true
• Export snapshot JSON and verify each request includes a schema object with request.headers, request.body, response.headers, response.body
• Test with array responses containing mixed types — schema items should show mixed type with variants

🤖 Generated with Claude Code

[linear]

GLA-46 Schema inference

From a single observation, extract a typed schema for both request and response.

• Headers: field names + value types, flag auth headers (Authorization, x-auth-token, bearer tokens, cookies used as auth)
• Payload: field names + inferred types (string, number, boolean, null, array, object), handling both JSON and form data
• Same treatment for response headers and response body

Done when a single request produces a structured schema object.