Replace component reconciliation with a projectional core

[merryman]

Summary

• replace the legacy component reconciler with a semantic component document, reducers, and explicit source/runtime projectors
• coordinate source, runtime, policy-cache, derived-component, and undo/redo updates as reversible transactions
• support scalar properties, rich text and embedded morphs, structural edits, parts, typed morphs, inherited state, layouts, masters, and cross-module derived propagation
• add deterministic fuzzing, invariants, regression coverage, and projection performance benchmarks
• remove the legacy reconciliation implementation, fallbacks, and now-unreachable helper code

Why

The former reconciliation path had accumulated overlapping mutation logic and recurring edge-case failures. The new projectional core gives every direct manipulation an explicit semantic command and validates the projected source and runtime state at transaction boundaries.

Impact

Direct component manipulation now uses one projectional path with exact undo/redo and derived-component propagation. Rich-text attribute edits use a fast path, while embedded submorphs and structural changes remain transactionally synchronized with source.

Validation

• complete branch suite before the final dead-code cleanup: 2,114 passed, 32 skipped, 0 failed
• ./scripts/test.sh lively.ide lively.halos
• deterministic reconciliation fuzz tests and projection invariants
• staged diff and whitespace validation

Supersedes #1807 after renaming the head branch to the required robin/ prefix.