Auto-generated API doc: doxygen → custom Python emitter → doc/api/.

`cmake --build build --target doc` runs Doxygen to produce XML, then
`doc/gen_api_md.py` (~330 lines, stdlib-only) emits a Markdown tree
under `doc/api/` that gitea renders directly in its file browser.

- 24 class/struct pages + 51 source-file pages + indices, with source
  links of the form `../../../../src/...#L42` that gitea turns into
  clickable line-anchored links.
- Doxyfile.in templated by CMake (XML-only output to build/doc/xml/).
- Pure Python emitter, zero external deps — no doxybook2 (not packaged
  on Arch) and no moxygen (avoids Node).
- Target gracefully disabled if Doxygen or Python 3 is missing at
  configure time; regular build target unaffected.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

doc/api/files/nets_8hpp.md

@@ -0,0 +1,29 @@
+# nets.hpp
+
+Source: [nets.hpp](../../../../src/system/nets.hpp)
+
+## Defines
+
+- [Net](../classes/Net.md)
+
+## Free Functions
+
+### `Net find_net(System *sys, Module *m, Signal *s)`
+
+📍 [nets.hpp:21](../../../../src/system/nets.hpp#L21)
+
+### `Net find_net(System *sys, Pin *pin)`
+
+📍 [nets.hpp:24](../../../../src/system/nets.hpp#L24)
+
+### `std::vector< Net > compute_all_nets(System *sys)`
+
+📍 [nets.hpp:28](../../../../src/system/nets.hpp#L28)
+
+### `bool net_type_consistent(const Net &net, SignalType &dominant)`
+
+📍 [nets.hpp:32](../../../../src/system/nets.hpp#L32)
+
+---
+
+← [Back to files](index.md) · [Top](../index.md)