feat: send Merkle roots

[0xIryna]

Proposed changes:

• add an owner-only function to set Merkle Tree Builder contract to HubPortal
• add sendMerkleRoots function to HubPortal that reads earners and earn managers Merkle tree roots, adds them to the additional payload and sends zero amount transfer message with this additional payload to Solana

[github-actions]

Changes to gas cost

Generated at commit: 33881281bbfba04f78f048f2c3b943afe30a6f66, compared to commit: dbe93da561c94dfc04beec8a144b11b287957b7a

🧾 Summary (20% most significant diffs)

Contract	Method	Avg (+/-)	%
HubPortal	currentIndex owner	+67 ❌ +64 ❌	+3.95% +2.67%
SpokePortal	currentIndex	+24 ❌	+2.17%

---

Full diff report 👇

Contract	Deployment Cost (+/-)	Method	Min (+/-)	%	Avg (+/-)	%	Median (+/-)	%	Max (+/-)	%	# Calls (+/-)
HubPortal	5,843,628 (-188,036)	attestationReceived chainId currentIndex disableEarning enableEarning initialize mode owner registrar sendMTokenIndex sendRegistrarKey sendRegistrarListStatus setPeer setSupportedBridgingPath setTransceiver tokenDecimals transfer transferMLikeToken	54,200 (+257) 293 (-22) 841 (+67) 2,454 (-16) 2,634 (+6) 127,237 (+90) 309 (-22) 2,463 (+64) 305 (-22) 3,157 (+71) 5,976 (+93) 6,424 (+95) 54,101 (+18) 27,402 (-22) 188,482 (+14) 3,821 (+71) 129,405 (+770) 122,537 (+703)	+0.48% -6.98% +8.66% -0.65% +0.23% +0.07% -6.65% +2.67% -6.73% +2.30% +1.58% +1.50% +0.03% -0.08% +0.01% +1.89% +0.60% +0.58%	82,824 (+266) 293 (-22) 1,765 (+67) 10,107 (-13) 30,728 (+1) 127,240 (+90) 309 (-22) 2,463 (+64) 305 (-22) 37,019 (+184) 37,472 (+206) 38,089 (+208) 54,101 (+18) 27,402 (-22) 188,482 (+14) 3,821 (+71) 129,405 (+770) 145,031 (+709)	+0.32% -6.98% +3.95% -0.13% +0.00% +0.07% -6.65% +2.67% -6.73% +0.50% +0.55% +0.55% +0.03% -0.08% +0.01% +1.89% +0.60% +0.49%	92,366 (+269) 293 (-22) 1,761 (+67) 12,659 (-12) 29,571 (0) 127,237 (+90) 309 (-22) 2,463 (+64) 305 (-22) 37,019 (+184) 37,472 (+206) 38,089 (+208) 54,101 (+18) 27,402 (-22) 188,482 (+14) 3,821 (+71) 129,405 (+770) 145,031 (+709)	+0.29% -6.98% +3.96% -0.09% 0.00% +0.07% -6.65% +2.67% -6.73% +0.50% +0.55% +0.55% +0.03% -0.08% +0.01% +1.89% +0.60% +0.49%	92,366 (+269) 293 (-22) 2,708 (+67) 12,659 (-12) 62,809 (0) 127,283 (+90) 309 (-22) 2,463 (+64) 305 (-22) 70,881 (+296) 68,968 (+318) 69,754 (+320) 54,101 (+18) 27,402 (-22) 188,482 (+14) 3,821 (+71) 129,405 (+770) 167,526 (+715)	+0.29% -6.98% +2.54% -0.09% 0.00% +0.07% -6.65% +2.67% -6.73% +0.42% +0.46% +0.46% +0.03% -0.08% +0.01% +1.89% +0.60% +0.43%	4 (0) 1 (0) 6 (0) 4 (0) 11 (0) 25 (+1) 1 (0) 2 (0) 1 (0) 2 (0) 2 (0) 2 (0) 46 (+24) 92 (+4) 25 (+1) 2 (0) 1 (0) 2 (0)
SpokePortal	5,482,133 (-347,597)	attestationReceived currentIndex initialize setPeer setTransceiver transfer transferMLikeToken	54,156 (+279) 1,129 (+24) 127,215 (+90) 54,079 (+18) 188,482 (+36) 131,365 (+1,209) 131,506 (+1,209)	+0.52% +2.17% +0.07% +0.03% +0.02% +0.93% +0.93%	105,505 (+291) 1,129 (+24) 127,215 (+90) 54,079 (+18) 188,482 (+36) 131,365 (+1,209) 153,978 (+1,215)	+0.28% +2.17% +0.07% +0.03% +0.02% +0.93% +0.80%	112,050 (+321) 1,129 (+24) 127,215 (+90) 54,079 (+18) 188,482 (+36) 131,365 (+1,209) 153,978 (+1,215)	+0.29% +2.17% +0.07% +0.03% +0.02% +0.93% +0.80%	217,340 (+333) 1,129 (+24) 127,215 (+90) 54,079 (+18) 188,482 (+36) 131,365 (+1,209) 176,450 (+1,221)	+0.15% +2.17% +0.07% +0.03% +0.02% +0.93% +0.70%	11 (0) 1 (0) 16 (0) 16 (0) 16 (0) 1 (0) 2 (0)

[github-actions]

LCOV of commit 6fa72eb during Forge Coverage #251

Summary coverage rate:
  lines......: 99.2% (260 of 262 lines)
  functions..: 96.5% (55 of 57 functions)
  branches...: 96.6% (28 of 29 branches)

Files changed coverage rate:
                             |Lines       |Functions  |Branches    
  Filename                   |Rate     Num|Rate    Num|Rate     Num
  =================================================================
  src/HubPortal.sol          |22.0%     50| 0.0%    11|    -      0
  src/Portal.sol             |22.6%     93| 100%    19|    -      0
  src/libs/PayloadEncoder.sol|20.4%     49| 0.0%    10|    -      0

[PierrickGT]

Could be useful to check that the address being set is not address zero.
Even if it can be set at any time.