feat: add organization usage report

[Siddhant-K-code]

Description

Adds agent-strace org-report for monthly organization-wide session volume, offline estimated cost, team/workspace breakdowns, heuristic task categories, and statistically guarded anomaly callouts.

The command reads either a shared trace directory (including workspace stores) or an explicitly selected authenticated remote collector. Remote reads use the existing collector API with strict authentication, TLS/URL/redirect/proxy, response-size, nesting, schema, tenant, and partial-report protections. Reports support text, versioned JSON, self-contained HTML, exact team/workspace scoping, cost/identity coverage, and report-local anonymization.

All cost, classification, and anomaly fields are explicitly labeled as estimates or heuristics. Collector and shared-directory inputs disclose their non-transactional snapshot limitation.

Documentation covers setup, security boundaries, privacy, and interpretation. Version is bumped to 0.91.0.

Closes #214

Validation

• Repository Ona test task: 1,835 Python tests passed
• VS Code extension: compile plus 3 tests passed
• Focused org-report suite: 21 tests passed
• Independent report/math/privacy review: approved
• Independent collector/security/tenancy review: approved
• git diff --check and source compilation passed

[Siddhant-K-code]

Independent review completed before opening this PR.

• Report/math/privacy review: approved after correcting cost denominators, peer baselines/sample floors, attribution identity, alias leakage, UTC filtering, label conflation, and output safety.
• Collector/security/tenancy review: approved after adversarial tests for credential leakage through proxies/redirects, malformed URLs, truncated/oversized/deep/non-finite JSON, schema mismatch, cross-tenant streams, partial reads, and event-cache memory growth.
• Final local CI: repository Ona task succeeded with 1,835 Python tests and all 3 extension tests passing.

No unresolved review findings remain. Hosted branch checks are still required before merge.