docs: fix sub-README inaccuracies and stale comments

[alejoamiras]

What

Sub-README and comment accuracy fixes — every "comment that references something that isn't there" found in the audit:

• Token: "behaves as a standard ARC-20" → AIP-20 (only occurrence of "ARC-20" in the repo; the prefix slip is a likely root of the AIP/ARC confusion). Replaces the dead aztec-arc403-extensions link (404 since the Wonderland wind-down) with the ARC-403 forum thread. Documents the five #[only_self] internal ABI functions that were absent from the README.
• Escrow: the key-derivation docs claimed 4 master keys; the code derives 6 (mssk_m, fbsk_m were undocumented). Pipeline diagram, derive_keys doc, and the six individual derive_master_* functions are now documented; fixes the stale "all four" comment in key_derivation.nr.
• Vault: "will be addressed in a future update" (the to-address privacy leak) → honest status: no fix scheduled, with a pointer for signalling demand. Fixes a test comment referencing a nonexistent constructor_with_asset function.
• Dripper: states it is a dev utility intentionally outside automated test scope.
• NFT benchmark: removes commented-out dead code whose note didn't match the call it disabled.

Validation

Docs/comments only; the one .nr change is a doc-comment. Workspace compiles.

🤖 Generated with Claude Code

[github-actions]

Benchmark Comparison

CPU	Cores	RAM	Arch
AMD EPYC 7763 64-Core Processor	4	16 GiB	x64

Contract: escrow

🚦	Function	Gates			DA Gas			L2 Gas			Proving Time (ms)
		Base	PR	Diff	Base	PR	Diff	Base	PR	Diff	Base	PR	Diff
⚪	(partial) withdraw	486,936	486,936		3,744	3,744		587,800	587,800		14,165	13,692	-473 (-3.3%)
⚪	withdraw	331,210	331,210		832	832		499,700	499,700		11,392	10,895	-497 (-4.4%)
⚪	withdraw_nft	378,517	378,517		1,440	1,440		527,400	527,400		12,336	11,637	-699 (-5.7%)

Contract: logic

🚦	Function	Gates			DA Gas			L2 Gas			Proving Time (ms)
		Base	PR	Diff	Base	PR	Diff	Base	PR	Diff	Base	PR	Diff
⚪	get_escrow	390,359	390,359		192	192		456,000	456,000		12,506	12,064	-442 (-3.5%)
⚪	secret_key_to_public_keys	387,718	387,718		192	192		456,000	456,000		12,437	12,136	-301 (-2.4%)
⚪	share_escrow	303,989	303,989		1,952	1,952		520,700	520,700		11,051	10,714	-337 (-3.0%)

Contract: multitoken

🚦	Function	Gates			DA Gas			L2 Gas			Proving Time (ms)
		Base	PR	Diff	Base	PR	Diff	Base	PR	Diff	Base	PR	Diff
⚪	burn_private	260,810	260,810		832	832		499,700	499,700		10,121	10,055	-66 (-0.7%)
⚪	burn_public	223,823	223,823		416	416		638,292	638,292		9,702	9,673	-29 (-0.3%)
⚪	initialize_transfer_commitment	225,077	225,077		768	768		474,500	474,500		9,713	9,621	-92 (-0.9%)
⚪	mint_to_private	297,577	297,577		1,408	1,408		511,400	511,400		10,837	10,979	+142 (+1.3%)
⚪	mint_to_public	223,823	223,823		416	416		637,800	637,800		9,655	9,751	+96 (+1.0%)
⚪	transfer_private_to_commitment	264,328	264,328		1,024	1,024		511,400	511,400		10,163	10,156	-7 (-0.1%)
⚪	transfer_private_to_private	337,261	337,261		2,048	2,048		555,100	555,100		11,262	11,319	+57 (+0.5%)
⚪	transfer_private_to_public	307,363	307,363		1,056	1,056		714,677	714,677		10,897	11,000	+103 (+0.9%)
⚪	transfer_public_to_commitment	223,823	223,823		640	640		663,516	663,516		9,729	9,692	-37 (-0.4%)
⚪	transfer_public_to_private	298,128	298,128		1,024	1,024		683,958	683,958		10,820	10,786	-34 (-0.3%)
⚪	transfer_public_to_public	223,823	223,823		480	480		673,505	673,505		9,770	9,678	-92 (-0.9%)

Contract: nft

🚦	Function	Gates			DA Gas			L2 Gas			Proving Time (ms)
		Base	PR	Diff	Base	PR	Diff	Base	PR	Diff	Base	PR	Diff
⚪	burn_private	275,257	275,257		416	416		661,052	661,052		10,624	10,649	+25 (+0.2%)
⚪	burn_public	223,823	223,823		448	448		670,034	670,034		9,849	9,658	-191 (-1.9%)
⚪	mint_to_private	341,050	341,050		1,600	1,600		735,342	735,342		11,501	11,479	-22 (-0.2%)
⚪	mint_to_public	223,823	223,823		448	448		670,718	670,718		9,784	9,713	-71 (-0.7%)
⚪	transfer_private_to_private	249,719	249,719		832	832		499,700	499,700		10,022	9,917	-105 (-1.0%)
⚪	transfer_private_to_public	275,286	275,286		416	416		659,258	659,258		10,613	10,625	+12 (+0.1%)
⚪	transfer_public_to_private	292,460	292,460		992	992		683,268	683,268		10,722	10,718	-4 (-0.0%)
⚪	transfer_public_to_public	223,823	223,823		384	384		633,285	633,285		9,750	9,811	+61 (+0.6%)

Contract: token

🚦	Function	Gates			DA Gas			L2 Gas			Proving Time (ms)
		Base	PR	Diff	Base	PR	Diff	Base	PR	Diff	Base	PR	Diff
⚪	burn_private	303,652	303,652		1,024	1,024		713,843	713,843		10,964	10,840	-124 (-1.1%)
⚪	burn_public	223,823	223,823		448	448		672,518	672,518		9,761	9,697	-64 (-0.7%)
⚪	initialize_transfer_commitment	225,077	225,077		768	768		474,500	474,500		9,758	9,613	-145 (-1.5%)
⚪	mint_to_private	355,289	355,289		2,144	2,144		737,956	737,956		11,713	11,665	-48 (-0.4%)
⚪	mint_to_public	223,823	223,823		448	448		672,113	672,113		9,643	9,682	+39 (+0.4%)
⚪	transfer_private_to_commitment	260,673	260,673		992	992		511,400	511,400		10,120	10,057	-63 (-0.6%)
⚪	transfer_private_to_private	344,855	344,855		2,592	2,592		557,600	557,600		11,519	11,569	+50 (+0.4%)
⚪	transfer_private_to_public	303,708	303,708		1,024	1,024		713,990	713,990		10,914	10,990	+76 (+0.7%)
⚪	transfer_private_to_public_with_commitment	308,509	308,509		1,600	1,600		747,290	747,290		11,087	10,921	-166 (-1.5%)
⚪	transfer_public_to_commitment	223,823	223,823		576	576		662,496	662,496		9,745	9,854	+109 (+1.1%)
⚪	transfer_public_to_private	296,092	296,092		992	992		683,271	683,271		10,866	10,804	-62 (-0.6%)
⚪	transfer_public_to_public	223,823	223,823		448	448		672,515	672,515		9,650	9,645	-5 (-0.1%)

Contract: vault

🚦	Function	Gates			DA Gas			L2 Gas			Proving Time (ms)
		Base	PR	Diff	Base	PR	Diff	Base	PR	Diff	Base	PR	Diff
⚪	deposit_private_to_private	508,340	508,340		1,312	1,312		878,035	878,035		14,226	13,948	-278 (-2.0%)
⚪	deposit_private_to_private_exact	612,065	612,065		1,888	1,888		915,103	915,103		16,198	15,883	-315 (-1.9%)
⚪	deposit_private_to_public	436,085	436,085		768	768		862,060	862,060		13,142	13,005	-137 (-1.0%)
⚪	deposit_public_to_private	424,713	424,713		1,984	1,984		964,832	964,832		13,053	12,846	-207 (-1.6%)
⚪	deposit_public_to_private_exact	424,724	424,724		1,952	1,952		949,256	949,256		13,059	12,805	-254 (-1.9%)
⚪	deposit_public_to_public	223,823	223,823		832	832		897,350	897,350		9,716	9,590	-126 (-1.3%)
⚪	issue_private_to_private_exact	612,065	612,065		1,888	1,888		915,763	915,763		16,055	15,922	-133 (-0.8%)
⚪	issue_private_to_public_exact	484,820	484,820		1,344	1,344		899,785	899,785		13,951	13,759	-192 (-1.4%)
⚪	issue_public_to_private	346,165	346,165		1,376	1,376		921,448	921,448		11,602	11,383	-219 (-1.9%)
⚪	issue_public_to_public	223,823	223,823		832	832		898,040	898,040		9,671	9,509	-162 (-1.7%)
⚪	redeem_private_to_private_exact	614,859	614,859		1,888	1,888		915,610	915,610		16,379	16,014	-365 (-2.2%)
⚪	redeem_private_to_public	436,028	436,028		768	768		862,504	862,504		13,108	12,842	-266 (-2.0%)
⚪	redeem_public_to_private_exact	427,575	427,575		1,952	1,952		949,577	949,577		13,215	12,895	-320 (-2.4%)
⚪	redeem_public_to_public	223,823	223,823		832	832		897,872	897,872		9,775	9,559	-216 (-2.2%)
⚪	withdraw_private_to_private	511,134	511,134		1,312	1,312		878,245	878,245		14,266	14,095	-171 (-1.2%)
⚪	withdraw_private_to_private_exact	614,859	614,859		1,888	1,888		915,556	915,556		16,102	15,953	-149 (-0.9%)
⚪	withdraw_private_to_public_exact	484,763	484,763		1,344	1,344		900,019	900,019		13,939	13,743	-196 (-1.4%)
⚪	withdraw_public_to_private	440,832	440,832		2,528	2,528		967,143	967,143		13,202	13,140	-62 (-0.5%)
⚪	withdraw_public_to_public	223,823	223,823		832	832		898,175	898,175		9,618	9,641	+23 (+0.2%)