db/snapshotsync: resume caplin state dump per-type to avoid overlapping files

[sudeepdino008]

Problem

When a new Caplin beacon-state snapshot type is added to an already-populated datadir (e.g. the GLOAS BuilderPendingPayments table), seg publishable starts failing with overlapping and/or short snapshot files.

Root cause is in how state snapshots are dumped:

• BlocksAvailable() reports the minimum to across all state types. A newly added type has no files, so the global available slot collapses to 0 (or to that one lagging type's progress).
• DumpCaplinState used that single global from for every type and looped outer over types, inner over slot ranges with no per-type resume and no skip-if-exists.

So a restart re-dumped already-caught-up types from the lagging floor, slicing their existing base file (e.g. 000000-007150) into overlapping 50k sub-files, while the genuinely-new type never reliably caught up to head. Observed on a sepolia snapshotter:

• PendingDepositsDump — clean layout plus spurious 000000-000050 … 001400-001450 files overlapping its 000000-007150 base.
• BuilderPendingPayments — only reached 2.7M, never the head (10.4M).

Fix

Make the state dump resume per-type from each type's own coverage:

• Add blocksAvailableForType — last visible segment to for a single type.
• Add planStateDump — pure function that, given each type's availability and the target to, produces the per-type [from,to) dump jobs. A caught-up type yields no jobs (so its base file is never re-sliced); a new type still starts from genesis.
• DumpCaplinState now builds per-type availability and dumps the plan; the redundant global fromSlot parameter is dropped (callers updated).

This also makes dump order deterministic (sorted by type name) instead of relying on Go map iteration order.

Tests

• TestPlanStateDumpResumesPerType — covered types are not re-dumped, lagging types resume at their own availability, new/empty types start at 0.
• TestBlocksAvailableForType — last-segment semantics.

Written test-first (Red → Green); the initial failing version surfaced that a shared fromSlot floor would leave a genesis gap for brand-new types, which is why the parameter was removed.

[Copilot]

Pull request overview

This PR fixes Caplin beacon-state snapshot dumping so it resumes per snapshot type rather than using a single global “from” slot, preventing already-covered types from being re-dumped into overlapping sub-files when a new snapshot type appears in an existing datadir.

Changes:

• Add per-type availability lookup (blocksAvailableForType) and a deterministic per-type dump planner (planStateDump), then rework DumpCaplinState to execute that plan.
• Remove the redundant fromSlot argument from DumpCaplinState and update call sites.
• Add focused tests for per-type resume planning and per-type availability semantics.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
db/snapshotsync/caplin_state_snapshots.go	Introduces per-type availability + planned dump jobs; updates DumpCaplinState to avoid overlapping files and to dump deterministically.
db/snapshotsync/caplin_state_dump_test.go	Adds unit tests for per-type resume planning and blocksAvailableForType last-segment semantics.
cmd/capcli/cli.go	Updates CLI call site to the new DumpCaplinState signature.
cl/antiquary/state_antiquary.go	Updates antiquary call site to the new DumpCaplinState signature.

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[domiwei]

I left two correctness comments around per-type resume availability. Both are about avoiding new permanent gaps/overlaps in partial snapshot layouts.