refactor(ui): replace remaining inline icons with the shared icon module

[truongthinh1412]

Description

Completes the shared icon module migration requested in #208 (tranche 1: #220 created src/components/icons.tsx with 11 icons; #265 migrated one more glyph).

• Extends the shared icon module from 11 to 59 exports: adds an internal StrokeSvgIcon base for stroke-drawn glyphs (per-glyph stroke-width, viewBox, round caps/joins) plus 47 new components copied from the real pasted paths (22 fill, 25 stroke).
• Replaces all remaining 74 inline <svg> icon blocks across 33 non-test source files, preserving each call site's size, class, style, reactivity, and accessibility semantics — zero intended visual change.
• Replaces remaining text-glyph icon substitutes (✓/× status symbols in MergeReadinessPanel, 3 standalone × close glyphs) with CheckIcon/CloseIcon at size 12.
• Folds the single-glyph src/documents/DocumentIcon.tsx into the shared module; importers updated with explicit sizes matching its previous defaults (14/12/18/18).
• Adds src/components/icons.client.test.tsx rendering all 59 exports: default size 16, custom size, currentColor inheritance, aria-hidden/<title> behavior.
• All 59 exports are consumed by non-test code, so knip (lint:dead) stays green; depcruise reports no violations.

Deliberately deferred (happy to follow up in this PR if preferred):

• The ▶ disclosure glyph in ConnectPhoneModal — no byte-faithful filled-triangle component exists in the module; substituting a visibly different glyph would change rendering.
• The svg-string constants in src/lib/mermaid-lightbox.ts — plain .ts building HTML strings, outside the module's .tsx scope.

If one 39-file PR is too large, I'm happy to split it into smaller tranches on request.

Issues Resolved

Fixes #208

Check List

• New functionality includes testing.
• New functionality has been documented in the README if applicable. (Not applicable — refactor only, no user-facing feature or configuration change.)

[truongthinh1412]

Rebased onto current main (78a65db) to resolve the merge conflicts — no review action needed, this just keeps the PR mergeable.

What the rebase involved, in case it's useful context:

• Upstream's document-workspace rewrite (DocumentWorkspaceOverlay → DocumentWorkspacePanel) was merged with the icon migration intact (including the 18px default-size restoration).
• Icons introduced upstream in the meantime were migrated to the shared module as well, so the PR still holds its "no inline icon SVGs" claim: the new focus-mode toggle (added as EnterFocusIcon/ExitFocusIcon), the full-width toggle (FullWidthIcon), the branch chip (GitBranchAltIcon), the "Advanced options" disclosure chevron in NewTaskPanel (ChevronRightThinIcon), and the tour-ready ✓ in ChangeTourButton (CheckIcon). Module now exports 65 icons, all covered by the client test.
• All local gates re-run green after the rebase (npm run check, npm run check:static, full client suite, zero src/ unit failures).