feat(combat-report): finish attribute activity semantics and coverage

[pengx17]

Context

Draft PR #132 establishes concrete attribute-change semantics, but a few product decisions and coverage gaps remain. Track them here so the temporary design draft can be retired during cleanup.

Remaining work

• Finish the pure effect-definition → concrete attribute type/operation resolver, covering base abilities, enchantment abilities, auras, and unresolved/transformed sources.
• Extend the optional report-event subtype/operation contract without breaking schema-v1 readers; cover unique, ambiguous, and unresolved attribution.
• Consolidate the viewer attribute descriptor table so class, unit, sign policy, native icon semantic, timeline, Inspector, and statistics policies have one owner.
• Decide and implement statistics behavior for Ammo gain/reload versus spend, including target-level aggregate detail.
• Keep custom/unknown attributes explicit and visibly unclassified.

Coverage

• Fixture coverage: HealthMax (Pasta/Boar Roast), Multicast loss after Ice Swan destruction, Damage/Crit/Cooldown modifiers, Ammo gain/loss, and actual destroy versus DestroyTargets.
• Representative-report census: no raw per-frame Cooldown/Haste/Slow/Freeze modifier rows.
• Playwright coverage for lane placement, source/target mode, diffs, native icons, Inspector detail, and statistics target breakdown.
• Validate one freshly recorded report with the updated DLL; retain conservative behavior for legacy reports.

Product decisions

1. Economy/progression changes: combat statistics or Inspector only.
2. Unknown Custom_*: visible by default or behind a diagnostic disclosure.
3. Ammo: gained/spent columns or signed net with tooltip breakdown.

Acceptance criteria

• The remaining decisions are resolved and encoded in one semantic descriptor source.
• All listed fixture, census, browser, and fresh-recording checks pass.
• No event is presented as a concrete attribute change unless its subtype/operation is supported by serialized evidence.