codedb_remote: use wiki backend only

[justrach]

Summary

• make codedb_remote route only to api.wiki.codes
• remove the stale codegraff/default action surface from the MCP schema
• normalize owner/repo inputs with the same slug rules as cloud ingest, so repos like vercel/next.js resolve to vercel-next-js

Validation

• zig build test
• zig build -Doptimize=ReleaseFast
• MCP smoke: schema only advertises wiki, repo=vercel/next.js action=tree returns vercel-next-js, backend=codegraff is rejected locally before any HTTP request

[github-actions]

Benchmark Regression Report

Thresholds: 10.00% and 50,000 ns absolute delta

NOISE means the percentage threshold was exceeded, but the absolute delta was too small to fail CI.

Tool	Base (ns)	Head (ns)	Delta	Abs Delta (ns)	Status
codedb_bundle	507392	499456	-1.56%	-7936	OK
codedb_changes	52754	55454	+5.12%	+2700	OK
codedb_deps	9451	10083	+6.69%	+632	OK
codedb_edit	6069	5460	-10.03%	-609	OK
codedb_find	60994	60530	-0.76%	-464	OK
codedb_hot	99558	101057	+1.51%	+1499	OK
codedb_outline	271861	270219	-0.60%	-1642	OK
codedb_read	87817	89495	+1.91%	+1678	OK
codedb_search	178264	176382	-1.06%	-1882	OK
codedb_snapshot	258084	243604	-5.61%	-14480	OK
codedb_status	213808	205897	-3.70%	-7911	OK
codedb_symbol	58105	57880	-0.39%	-225	OK
codedb_tree	45665	43765	-4.16%	-1900	OK
codedb_word	68609	69968	+1.98%	+1359	OK

[github-actions]

Benchmark Regression Report

Thresholds: 10.00% and 50,000 ns absolute delta

NOISE means the percentage threshold was exceeded, but the absolute delta was too small to fail CI.

Tool	Base (ns)	Head (ns)	Delta	Abs Delta (ns)	Status
codedb_bundle	498707	495717	-0.60%	-2990	OK
codedb_changes	58706	54570	-7.05%	-4136	OK
codedb_deps	9326	8879	-4.79%	-447	OK
codedb_edit	6320	6163	-2.48%	-157	OK
codedb_find	59007	61341	+3.96%	+2334	OK
codedb_hot	106688	96415	-9.63%	-10273	OK
codedb_outline	262780	270793	+3.05%	+8013	OK
codedb_read	90785	99991	+10.14%	+9206	NOISE
codedb_search	175212	177841	+1.50%	+2629	OK
codedb_snapshot	259238	270548	+4.36%	+11310	OK
codedb_status	214785	219066	+1.99%	+4281	OK
codedb_symbol	61101	60662	-0.72%	-439	OK
codedb_tree	43479	42721	-1.74%	-758	OK
codedb_word	69600	67342	-3.24%	-2258	OK