Continuations cleanup: docs, comments, and regression tests

[MauroToscano]

Follow-up cleanup on top of #685 (continuations), targeting the continuations-local-to-global branch so it can be folded into the PR.

This version intentionally leaves the performance changes out so they can be rechecked separately.

Soundness-regression tests

The production code is correct today; these guard against silent regressions of the main continuation properties:

• L2G MU selector — MU=0 on a touched row, MU=1 on padding, and MU=2 non-boolean are each rejected.
• Design-Y orphan / chain-truncation (MU=0 on a later epoch's row) is rejected.
• init_epoch < fini_epoch ordering arithmetic for self/future references.
• Tampered EpochProof.l2g_root is rejected, covering the epoch-to-global L2G root binding.
• A private-input program proven as a multi-epoch continuation verifies.

Cleanup

• Replace bare 508 literals with register_base_address(254).
• Remove the unused DEFAULT_EPOCH_SIZE; note run_epochs as a test/bench helper.
• Docs: drop the non-existent page_configs bundle field from design section 8, register the design doc in SUMMARY.md, and correct the global_memory column table.
• Fix the stale test comment about L2G-root binding coverage.

Verification

• make lint
• cargo test --release -p lambda-vm-prover local_to_global_bus_tests
• cargo test --release -p lambda-vm-prover test_split_verify_rejects_tampered_l2g_root

Deferred

• Streaming --num-epochs cycle counting.
• Skipping the redundant per-epoch L2G trace build inside from_image_and_logs.

[github-actions]

Benchmark Results for unmodified programs 🚀

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base binary_search	60.6 ± 2.6	58.5	67.8	1.03 ± 0.05
head binary_search	59.0 ± 0.6	58.3	60.4	1.00

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base bitwise_ops	59.9 ± 1.5	58.4	61.4	1.03 ± 0.03
head bitwise_ops	58.4 ± 0.9	57.9	61.0	1.00

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base ecsm	3.3 ± 0.1	3.1	3.5	1.00
head ecsm	3.4 ± 0.2	3.2	3.7	1.03 ± 0.06

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base fibonacci_26	63.9 ± 1.4	63.0	67.0	1.00 ± 0.03
head fibonacci_26	63.6 ± 0.8	62.7	64.8	1.00

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base hashmap	131.8 ± 4.0	125.7	137.7	1.00
head hashmap	134.5 ± 2.8	130.4	140.1	1.02 ± 0.04

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base keccak	126.5 ± 2.6	121.0	128.9	1.00
head keccak	128.7 ± 2.5	125.5	134.9	1.02 ± 0.03

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base matrix_multiply	66.2 ± 1.5	63.5	68.3	1.00 ± 0.03
head matrix_multiply	65.9 ± 1.4	64.0	67.9	1.00

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base modular_exp	59.2 ± 0.5	58.4	60.2	1.00
head modular_exp	59.6 ± 0.7	58.5	60.6	1.01 ± 0.01

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base quicksort	63.4 ± 0.5	62.6	63.9	1.00
head quicksort	63.6 ± 0.6	62.6	64.8	1.00 ± 0.01

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base sieve	64.8 ± 0.5	64.4	65.7	1.00
head sieve	65.4 ± 0.6	64.5	66.3	1.01 ± 0.01

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base sum_array	75.3 ± 3.3	73.3	84.1	1.00
head sum_array	79.2 ± 14.8	73.5	121.3	1.05 ± 0.20

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base syscall_commit	91.5 ± 0.8	90.6	92.7	1.00 ± 0.01
head syscall_commit	91.2 ± 0.7	90.5	92.4	1.00