fix: send request headers from HTTP helpers and http data source (#80)

[geoffjay]

Summary

Fixes #80 — the Rhai HTTP helpers and the http data source had no way to set request headers, so a config could not send Authorization: Bearer <token> (or any custom header) and every authenticated call failed.

Changes

• Rhai helpers (crates/nemo-extension/src/rhai_engine.rs): execute_http_request gained an optional headers map, and each helper got a header-accepting arity:

  • http_get(url, #{…}), http_delete(url, #{…})
  • http_post(url, body, #{…}), http_put(url, body, #{…})

  A caller-supplied Content-Type overrides the JSON default applied to request bodies. Headers are flattened to owned string pairs before the async boundary since rhai::Dynamic is !Send.

• http data source (crates/nemo-data/src/sources/mod.rs): the factory previously parsed only url/interval and silently dropped method/headers/body, even though HttpSourceConfig and fetch() already applied them. It now parses all three. New parse_http_headers accepts either a config object or a JSON-string attribute. ${env.X} / ${var.x} in header values are resolved by the config resolver at load time.

• Schema (crates/nemo-registry/src/builtins.rs): added headers and body to the http data source schema so configs validate.

Usage

http_post(url, body, #{ "Authorization": "Bearer " + token })

<source name="secure" type="http" url="https://api.example.com/me"
        headers='{"Authorization":"Bearer ${env.API_TOKEN}"}' />

Testing

• Affected crates build clean; clippy + fmt clean (pre-commit hooks passed).
• Added 3 parse_http_headers unit tests (object / JSON-string / none); nemo-registry and nemo-extension suites green.

Docs updated: KB data-flow.md, extensions.md, log.md; the nemo-xml-reference skill; and docs/public/configuration.md.

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 40.24390% with 49 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.45%. Comparing base (82b766c) to head (b34f408).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/nemo-extension/src/rhai_engine.rs	0.00%	43 Missing ⚠️
crates/nemo-data/src/sources/mod.rs	83.78%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #88      +/-   ##
==========================================
- Coverage   56.59%   56.45%   -0.14%     
==========================================
  Files          78       78              
  Lines        6866     6943      +77     
==========================================
+ Hits         3886     3920      +34     
- Misses       2980     3023      +43     

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