feat: add an Extra Usage Limit widget - #756

sirmalloc#755 live picker preview, sirmalloc#754 fast mode widget, sirmalloc#753 thinking-effort test stub, sirmalloc#752 transcript block fallback fixes, sirmalloc#751 editor keys no longer pause on global install lookup, sirmalloc#750 git cache TTL starts after the run, sirmalloc#749 npx cache skip, sirmalloc#747 Block Usage hides at 100% and swaps with Block Reset Timer)

Conflict policy: upstream infra wins, fork features ported on top. Joins:
sirmalloc#750 stamps the git cache after the run while keeping the fork's execGit
hardening/env snapshot and daemon prefetch bookkeeping; sirmalloc#752's
isApiErrorMessage guard lands in the fork's shared collectTimestampFromLine
(sync + async twins), upstream's duplicate getActivityTimestamp dropped;
sirmalloc#747 adds SESSION_AT_LIMIT alongside the fork's zero hide state
(BlockResetTimer keeps zero + under-limit via isAtSessionLimit, SessionUsage
is no-data/zero/at-limit); sirmalloc#755 replaces the fork's picker window + "Showing
X-Y of N" note with upstream's renderWindowedList/getPickerMaxVisible and
live preview (markers ↑/↓ N more cover the counts); sirmalloc#751's installationState
useMemo replaces the fork's inline lookups, the fork's mainMenuIndex helper
is kept.

Co-Authored-By: Claude Code <[email protected]>

Upstream: Extra Usage Limit widget (sirmalloc#756), live widget preview while picking (sirmalloc#755), Fast Mode widget (sirmalloc#754), transcript block fallback fixes (sirmalloc#752), editor keys on a global install (sirmalloc#751), git cache TTL (sirmalloc#750), npx cached copy skip (sirmalloc#749), Block Usage hide at 100% (sirmalloc#747), Block Reset Timer hide until 100% (sirmalloc#697), fish-style branch abbreviation (sirmalloc#614), jj detached HEAD (sirmalloc#705), hooks save warning (sirmalloc#703), dev reload (sirmalloc#700), merge ends at a hidden widget (sirmalloc#698), Block Forecast and Block Limit Timer widgets (sirmalloc#699), contributor guide (sirmalloc#706), POSIX path case fix (sirmalloc#707), whitespace-distinct conflict filenames (sirmalloc#709), Quick Start reorder (sirmalloc#715), bunx launch guidance (sirmalloc#714), jj diff summary counts (sirmalloc#711), powerline manual separators (sirmalloc#713), keychain credential by account (sirmalloc#532), Keychain probe timeout (sirmalloc#760), usage cache scoped per CLAUDE_CONFIG_DIR (sirmalloc#266), test isolation (sirmalloc#717, sirmalloc#753), dev-dependency bumps (sirmalloc#745)

Conflicts resolved per the standard-resolution table; fork deletions re-applied.

Hand edits outside conflicts:
- src/utils/global-command-resolution.ts: fork-rename (ccstatusline@ -> ccstatusline-usage@ in upstream's new bunx pattern)
- src/utils/__tests__/global-package-manager.test.ts: fork-rename (package dir ccstatusline-usage in upstream's new tests)
- src/utils/usage-fetch.ts: compat fix - cacheUsageData gained a fetchedAtMs arg (upstream sirmalloc#266); adapted the fork-only fetchFreshUsageData call site
- src/utils/__tests__/usage-fetch.test.ts: compat fixes - cache/lock now hashed per CLAUDE_CONFIG_DIR (usageFilePath helper) in four fork tests; upstream fableUsage renamed to fork's weeklyFableUsage; seedUsageCache takes TokenHome
- src/utils/__tests__/usage-prefetch.test.ts: compat fix - mockFetchUsageData renamed to upstream's mockFetchUsage in cleanly-merged tests
- README.md: took upstream's Quick Start move (sirmalloc#715) and dropped the fork's old copy; fork-rename of its ccstatusline@ specifiers; links to fork-deleted docs (docs/USAGE.md, docs/WINDOWS.md) replaced with the fork's inline text
- CONTRIBUTING.md: links to the fork-deleted docs/DEVELOPMENT.md pointed at the README Development section
- docs/test-retirements.md: ledger entries for the 12 upstream test renames (sirmalloc#697, sirmalloc#698, sirmalloc#700, sirmalloc#705, sirmalloc#713, sirmalloc#760)

Brings in upstream main through #41, which now holds #33 as upstream
sirmalloc#756. Main adds Extra Usage Limit at the same places the #33 branch
merged here did, so the widget manifest, the usage prefetch's widget list
and requirements, and its prefetch test keep main's single entry. Daily
Cost Rate's billed-spend test stubs getUsageFetchedAtMs, which #36 now
reads in place of its own getUsageFetchedAt.

# Conflicts:
#	docs/USAGE.md
#	src/ccstatusline.ts
#	src/types/RenderContext.ts