Stop shipping megabytes of skill prompts in every snapshot refresh

The whole app turned to molasses because snapshot.load() shipped the
entire skill_runtime_snapshots table - unbounded, compiled_prompt
included - over IPC on every refresh. A real profile carried 142 rows
totaling 144MB (1.1MB each from the pre-cap CEO compile-all era), so
every coalesced refresh serialized ~144MB of JSON. The forced-humanizer
rework made it worse by adding a row per run for every agent.

- Drop skillRuntimeSnapshots, skillRevisions, skillTests, and
  skillBindings from the renderer snapshot: no renderer surface reads
  them; skill internals are main-process state. Only the lightweight
  skillDefinitions catalogue still ships.
- Project provider_requests without raw_response_json (4.1MB across the
  newest 100 rows; RunsPage only reads responseText)
- Migration 051 purges the bug-era compiled prompts from existing DBs
- resolveRuntimeSnapshot is now idempotent per run: a run re-queued by
  startup recovery reuses its frozen snapshot instead of dying on the
  uniqueness guard and burning real retry budget
- Regression test pins the contract: a 2MB database row must not add
  bytes to the snapshot (payload asserted under 400KB)

src/shared/provider-request-domain.ts

@@ -10,6 +10,11 @@ export const PROVIDER_REQUEST_STATE = {
 
 export type ProviderRequestState = typeof PROVIDER_REQUEST_STATE[keyof typeof PROVIDER_REQUEST_STATE];
 
+/**
+ * Snapshot projection of a provider request. The raw provider response body
+ * stays in the database (task_runs diagnostics read it there) — shipping it
+ * to the renderer ballooned every snapshot by megabytes for nothing.
+ */
 export interface ProviderRequestRecord {
   id: string;
   orgId: string;
@@ -19,7 +24,6 @@ export interface ProviderRequestRecord {
   model: string;
   promptSha256: string;
   responseText: string | null;
-  rawResponseJson: string | null;
   state: ProviderRequestState;
   errorMessage: string | null;
   inputCharCount: number;

src/shared/snapshot-domain.ts

@@ -34,11 +34,7 @@ import type {
   ProviderCatalogEntry,
   ProviderRecord,
   ScheduledPostRecord,
-  SkillBindingRecord,
   SkillDefinitionRecord,
-  SkillRevisionRecord,
-  SkillRuntimeSnapshotRecord,
-  SkillTestRecord,
   SprintRecord,
   TaskRecord,
   TaskRunRecord,
@@ -103,11 +99,11 @@ export interface AppSnapshot {
   providerRequests: ProviderRequestRecord[];
   providerRateLimits: ProviderRateLimitStateRecord[];
   providerRateLimitObservations: ProviderRateLimitObservationRecord[];
+  // The snapshot is the renderer's working set and rides IPC on every
+  // refresh. Skill internals (revisions, bindings, per-run runtime
+  // snapshots with compiled prompts) are main-process concerns and stay out
+  // of it; only the lightweight catalogue listing ships.
   skillDefinitions: SkillDefinitionRecord[];
-  skillRevisions: SkillRevisionRecord[];
-  skillBindings: SkillBindingRecord[];
-  skillRuntimeSnapshots: SkillRuntimeSnapshotRecord[];
-  skillTests: SkillTestRecord[];
   socialAccounts: SocialAccountRecord[];
   socialAccountGrants: SocialAccountGrantRecord[];
   browserSessionContainers: BrowserSessionContainerRecord[];